THE SIEGE OF EARTH

c. AD 1,000,000

I

The canal cut a perfect line across the flat Martian landscape, arrowing straight for the crimson rim of sun at the horizon.

Walking along the canal’s bank, Symat was struck by the sheer scale on which people had reshaped the landscape for a purpose - in this case, to carry water from Mars’s perpetually warm side to the cold. Of course the whole world was engineered, but terraforming a world was beyond Symat’s imagination, whereas a canal was not.

His mother had always said he had the instincts of an engineer. But it wasn’t likely he would ever get to be an engineer, for this wasn’t an age when people built things. A million years after the first human footsteps had been planted in its ancient soil, Mars was growing silent once more.

Symat was fourteen years old, however, and that was exactly how old the world was to him. And he was unhappy for much more immediate reasons than man’s cosmic destiny. He stumbled on, alone.

It was hours since he had stormed out of his parents’ home, though the changeless day made it hard to track the time. Nobody knew where he was. He had instructed the Mist, the ubiquitous artificial mind of Mars, not to follow him. But the journey had been harder than he had expected, and he was already growing hungry and thirsty.

It might have been easier if his journey had a destination, a fixed end. But he wasn’t heading anywhere as much as escaping. He wanted to show his parents he was serious, that his refusal to join the great exodus from reality through the transfer booths wasn’t just some fit of pique. Well, he’d done that. But his flight had a beginning but no end.

Trying to take his mind off his tiredness, he stared into the sliver of sun on the horizon. Sol was so big and red it didn’t hurt his eyes, even when he gazed right into it. The sun never moved, of course, save for its slow rise as you walked towards it.

The sky of Mars had changed, across a million years. Symat knew that Mars’s sky had once had three morning stars, the inner planets. But Venus and Mercury had long been eaten up by the sun’s swelling, Earth wafted away, and Mars was the closest of the sun’s remaining children.

And that sun never shifted in the sky. These days Mars kept one face turned constantly towards the sun, and one face away from it: one Dayside, one Nightside, and a band of twilight between where the last people lived.

Something briefly eclipsed the sun. He stopped, blinking; his eyes were dry and sore. He saw that he had passed through the shadow of a spire.

He walked on.

Soon he entered a city. The buildings were tall and full of sunlight, and bridges fine as spider web spanned the canal water. But there were no people walking over those bridges, no flitters skimming around the spires, and red dust lay scattered over the streets. It was like walking through a museum, solemn and silent.

One building bulged above his head, a ball of smooth, fossil-free Martian sandstone skewered on a spire of diamond. Clinging to the bank of the canal Symat gave it a wide berth: even after all this time human instincts remained shaped by the heavier gravity of Earth, where such an imbalanced structure would have been impossible.

Time had made its mark. Right in the heart of the city one slender bridge had collapsed. He could see its fallen stones in the water, a line of white under the surface.

Before he reached the ruined abutment on the canal bank he came to a scattering of loose stones. He gathered together a dozen or so cobbles and peered up resentfully at one of the more substantial buildings. Its flat windows, like dead eyes, seemed to mock him. He hefted a cobble, took aim, and hurled it. His first shot clattered uselessly against polished stone. But his second shot took out a window that smashed with a sparkling noise. The sound excited him, and he hurled more stones. But the noise stopped every time he quit throwing, reminding him firmly he was alone.

Dispirited, he dumped the last of his cobbles and turned back to the canal. On its bank, he sat with his feet dangling over blue running water, water that ran endlessly from the world’s cold side to the warm.

Symat was very thirsty.

The canal bank was a wall of stone that sloped smoothly down to the water. It would be easy to slide down there, all the way into the water. He could drink his fill, and wash off the dust of Mars. But how would he get out? Glancing down the river he saw the ruins of that bridge. The bank beneath the abutment was broken up; surely he could find handholds.

Without water he was going to have to turn back. It was a defining moment in his odyssey.

Without letting himself think about it he pulled off his boots, pants and jacket, and slid down the smooth sloping wall. The water was so cold it shocked him, and it was deep; he couldn’t feel the bottom. When he came bobbing back up he was faintly alarmed that he had already been washed some way towards the stump of the bridge. The current must be stronger than it looked.

With a couple of strokes he reached the canal wall. It was smooth, but by pushing his hands against it he was able to resist the current. Feeling safer, he ducked his head and scrubbed his hair clean of dust, and took long deep draughts of the water. It was chill, for it was meltwater from Nightside, and slightly sparkling; Mars’s water was rich in carbon dioxide.

Refreshed, he felt his energy return. There were more cities strung out along the canal like pearls on a necklace. He could hide out for days, and how that would make his parents worry.

But he was starting to feel cold, deep inside. Time to get out. He pushed off from the wall and let himself drift downstream. When he reached the ruined abutment he grabbed at projecting stones. But they were all slick with some green slime, and slid maliciously out of his hands. Scared now, he shoved himself at the protruding stones. He managed to halt his slide down the river, but only by clinging on with all his limbs, like a spider, and the water still plucked at his legs and torso.

He was getting very cold, and tiring quickly, his muscles aching. He had walked along the canal for hours and had seen nothing but smooth walls. If he lost his grip here, he would be washed away until he drowned - or, even worse, the Mist would alert his parents, who would come sweeping down in the family flitter to rescue him. The first real decision he had made had been a stupid one, and all his defiant dreams of showing his parents he was worthy of their respect were imploding.

He was starting to shiver. He had no choice. He prepared to call for the Mist’s help.

`Up here.’

The voice came from above. Looking up, he saw three heads silhouetted against the sky, three small curious faces peering down. `Who are you?’

`Try there!’ The middle figure leaned over and pointed. It was a girl, a bit younger than he was. She was pointing at a shelf on the canal wall, all but invisible from his position down here. With an effort he lifted up his hand and grabbed at the shelf. It was dry and he grasped it easily, and already felt safer.

`All right,’ the girl called down. `Now see if you can reach that foothold. To your left, just behind that broken stone …’

In this way, with the girl spotting one hand-or foothold after another, he managed to haul himself up out of the water.

Exhausted, he flopped on his belly on the bank.

He got his first good look at the children who had helped him. They were a girl and two boys. The girl looked about twelve, and the boys, wide-eyed, were no more than eight or nine. They wore simple shifts of bright blue cloth that looked oddly clean. They weren’t alike, not like siblings, a family.

One of the boys approached him, and Symat reached out a hand. But there was a soft chime, and his fingers passed through the boy’s palm. The boy yelped and drew back, as if it had hurt.

Symat looked at the girl. `You’re Virtuals.’

She shrugged. `We all are. Sorry we can’t help you up.’

`I can manage.’ Not wanting to shame himself before this girl, he rolled on his back and sat up, panting hard.

The Virtuals stared at him. `My name is Mela,’ the girl said. `This is Tod, this is Chem.’

`I got stuck,’ Symat said, hotly embarrassed.

Mela nodded, but he saw the corners of her mouth twitch. `You ought to put your clothes back on before you get too cold.’

One of the boys, Tod, said in a piping voice, `We can’t get them for you.’

`Sorry,’ said the other, Chem. `Would you like some food?’

`Yes.’

`We’ll show you.’

Symat towelled himself on his jacket and dressed. His clothes dried quickly, and, sensing his low body temperature, warmed him. The three Virtual children watched him silently.

They led him into the city, away from the canal. They walked with a sound of rustling clothes, even of boots crunching on the scattered sand. But of the four of them only Symat left footprints.

`We saw you breaking the windows,’ Tod said. `Why did you do that?’

`Why not?’

Tod considered. `It’s wrong to break things.’

`But nobody’s coming back here. People are leaving the planet altogether. What difference does it make?’

`My parents are coming back,’ Chem said.

Mela said softly, `Chem-‘

`I wouldn’t throw stones,’ the boy said. `My parents wouldn’t like it.’

`What parents? … You couldn’t throw stones anyway,’ Symat said. `You’re a Virtual.’

That seemed to hurt the boy, and he glanced away.

Mela was slim, thoughtful, grave. She didn’t react to this exchange one way or another. But somehow she made Symat feel ashamed of upsetting the Virtual boy.

They came to a building, an unprepossessing block in a neighbourhood of crystalline spires. It was as unlit as the others. `There’s food in here,’ Tod insisted. `Through that door.’ They stood waiting for him to open the door.

`Why don’t you go in? You’re Virtuals. You could just walk through the wall.’

Mela said, `Protocol violations. We aren’t supposed to.’

`It hurts,’ Chem said.

Symat said, `I haven’t been around Virtuals much.’ He stepped forward, pushed at the door’s polished surface, and it slid open.

The building was an apartment block. They wandered through suites of rooms. Heavy furniture remained, chairs and tables and beds, but smaller items had been taken away.

`I’ve seen people take stuff,’ Symat said. `Clothes and ornaments and toys, even sets of plates to eat dinner. They carry them in suitcases and boxes when they go through.’

Mela asked, `Through where?’

`Through the transfer booths. Imagine carrying plates and forks and knives into another universe!’

`What are they supposed to take?’ Mela asked reasonably.

They came to a kind of kitchen, where a nanofood replicator was still functioning. Symat asked it to prepare him something warm, and soon rich smells filled the air.

`It probably needs restocking,’ Mela said. `You can scrape up some algae from the canal, I guess.’

Chem said sharply, `If you can keep from getting stuck!’ He and Tod laughed.

Mela reproved the boys. Symat sat at a table and ate in dogged silence. The Virtuals stood around the table, watching him.

Chem said, ‘Of course you won’t have to put more glop in the nanofood box if your parents come for you.’

`They won’t come,’ Symat said, chewing. Mela watched him with that quiet gravity, and he felt impelled to add, `They don’t know I’m here.’

`Are you hiding?’ Chem asked. `Did you run away?’

`Did you do something wrong?’ Tod asked, wide-eyed.

`They want me to go into a transfer booth with them. I don’t want to go.’

Chem said, `Why not?’

`Because it would feel like dying. I haven’t done with this world.’

Chem said brightly, `I’d go with my parents. I always do whatever they want.’

Tod said maliciously, `They would go without you. They probably have already.’

`No, they haven’t.’ Chem’s lips were working. `They’ll come back to me when-‘

`When, when, when,’ Tod sang. `When is never. They’re never coming back!’

`And nor are yours!’

`But I don’t care any more,’ Tod said. `You do. Ha ha!’

Chem, in a tearful fury, flew at Tod. The wrestling boys fell to the floor and crashed through table legs. Pixels flew and protocol-violation warnings pinged, but the table didn’t so much as quiver.

Symat watched curiously. He lived in a world saturated by sentience, where everything was aware, everything potentially had feelings. He understood Virtual children could be hurt, but he didn’t necessarily know what might hurt them.

`Enough.’ Mela waded into the mle and pulled the boys apart. Chem, crying copiously, ran from the room. Mela said to Tod, `You know how it upsets him when you say such things.’

`It’s true. Our parents are never coming back. His aren’t. We all know that.’

Mela put her hand on her heart. `He doesn’t know it. Not in here.’

`Then he’s stupid,’ Tod said.

`Maybe he is, maybe not. But we have to look out for him. All we have is each other now. Go after him.’

`Aww-‘ Tod pulled a face, but he went out obediently.

Mela looked at Symat. `Kids,’ she said, smiling faintly.

Symat, his head full of his own issues, chewed his food.

When he had done eating, the apartment was a little more like a home, a little less like a strange place. And, his muscles still aching from his time in the water, he realised he felt tired. He found a bathroom, and a bedroom stripped of light furnishings. He sat on a pallet.

The three Virtuals clustered in the doorway, looking at him.

`I’m going to sleep,’ he said.

`All right.’ They receded into the shadows.

Symat lay down on the pallet, and his clothes, sensing his intentions, fluffed themselves up into a warm cocoon around his body. Experimentally he ordered the room to dim its lights; the command worked. He turned over and closed his eyes.

He thought he slept.

But he heard murmuring. He saw the two boys in the dim light, standing at the foot of his pallet - no, hovering, their feet just above the ground. And they were talking, softly, and too rapidly for him to hear, like speeded-up speech. He heard a name: `The Guardians.’ Then one of them whispered, `He’s awake!’ And they fled, sliding through the solid wall like spectres, accompanied by a soft pinging.

So much for protocol violations, Symat said to himself. Those Virtuals were creepy. He didn’t understand where they had come from, what they wanted. But he reminded himself they were artificial; and like all artefacts they were here to serve humanity - him. He huddled down in his clothes and went back to sleep.

When he rose and walked out of the apartment into the unchanging sunlight, the three Virtuals were waiting for him. They were sitting on a low stone wall, or at least they looked like they were doing so, Mela in the centre with the two boys to either side.

`Um, thank you for bringing me to this place. The food.’

`You’re human. That’s our job,’ Mela said.

`I suppose it is. Thanks anyhow.’ He walked off down the street towards the canal.

When he looked back they were following. Perhaps they were waiting for him to give them more commands. He wouldn’t have admitted it, but he was glad to have some company.

Walking along the line of the canal they soon left the city behind. The canal continued to head towards the immobile sun, but now the water looked turbid, muddy.

While Mela walked with Symat, the two boys ran by themselves. They played elaborate games of hide and seek, which could involve hiding inside the fabric of a wall, which evidently didn’t hurt that much; the air was full of warning pings, and the laughter of the boys. It reminded Symat uneasily of their odd behaviour in the bedroom last night. Maybe they had been inhibited about violating their protocols around him. If so, the inhibition was wearing off.

They came to a small township, as empty as the city. The boys ran off to explore. Mela and Symat sat on a low wall.

He asked her, `How come I didn’t see you yesterday, before you found me in the canal?’

`We didn’t want you to see us.’

He wondered what a Virtual had to hide from. `Why does Chem talk about “parents”? Virtuals don’t have parents.’

`We did.’

It had been a craze, a few generations back. It began after humans had been pushed back to Sol system.

`People still wanted kids,’ Mela said. `But you don’t want to bring kids into a defeated world. So they had us instead.’

A Virtual child could be a very convincing simulacrum of the real thing. You could raise it from infanthood, teach it, learn from it. It would have been trivial to realise a child physically, downloading complex sensoria into a flesh-and-blood shell, but such `dolls’ were unpopular, apparently violating some even deeper set of instincts. It was more comfortable to be with Virtuals, even if you couldn’t cuddle them.

And Virtual kids actually had advantages. You could back them up, rerun favourite moments. You could even wipe them clean if you really made a hash of raising them, though sentience laws discouraged this.

One feature, popular but hotly debated ethically, was the ability to stop the growth of your child at a certain age. You could stretch out a childhood for as long as you wanted, enough to match your own long lifespan. Some people kept their Virtual children as perpetual infants; generally, however, eight to ten years old was the chosen plateau range.

`I’m twelve,’ Mela said. `Few ever got as old as me. For a long time I’ve been surrounded by kids younger than me.’

`A long time? How long?’

Mela considered. `Oh, two hundred years, nearly.’

Symat, shocked, didn’t know what to say.

Times changed, Mela said. Now, in increasing numbers, people were leaving the world behind altogether, passing through the transfer booths to an unknown destination beyond. And the Virtual children couldn’t follow: you could take your pots and pans, but you couldn’t take your Virtual child.

More than that, Mela told him mildly, Virtual children had simply gone out of fashion, as had so many technological toys before them. It became embarrassing to admit you needed such an emotional crutch.

For all these reasons, the children were shut down - or more commonly just abandoned, perhaps after centuries of companionship every bit as intense as the bond between a parent and a real child.

`Every last mother said she would come back. I always knew the truth. I was twelve years old. But Chem is only eight. He’ll be eight for ever. And he still believes. Every day he is disappointed.’

Every day for centuries, Symat thought, Chem wakes up full of pointless hope, trapped in childhood. `Tod seems to understand.’

`He’s actually younger than Chem, but he’s tougher minded.’

`How come?’

She shrugged. `His parents had him designed that way. You could choose what you liked. Chem’s parents must have wanted a child more dependent, more vulnerable.’

`But they abandoned him anyway.’

`Oh, yes.’

Symat said, `But I still don’t see-‘

He heard a piercing scream. Mela broke off and ran into the township. Symat hurried after her.

They came to an open plaza. A number of children had gathered, perhaps a dozen, none older than eight or nine. No, not children - they were more Virtuals, as Symat could tell from the sparkling pixels and tiny pings that marked petty protocol violations. They all wore bland shifts and coveralls like Mela and the boys.

And these kids stood in a loose ring around Chem and Tod. The boys crouched on the floor, clinging to each other.

Mela ran forward. `Get away from them!’

Symat hurried after her. `What kind of game is this?’

`No game,’ she called back. `They are bloodsuckers. They are trying to kill the boys.’

`Kill them? How do you kill a Virtual?’

Mela didn’t answer. She waded into the attacking children, grabbing them and pulling them aside. But there were too many of them; they gathered around her and pushed her back, jeering.

Symat ran forward, fists clenched. `Back off.’

One of the girls faced him. She was shorter than he was, with a hard, cold face and her skin was waxy, almost translucent. She had drifted a long way from her core programming, he realised. `Whose child are you?’

`I’m no child. I’m human.’

The girl jeered and pointed at Chem. `He thinks he’s human.’

Symat swung a hand at her face. His fingers passed through her pale flesh, scattering pixels. She flinched, shocked; that had hurt.

`Do what I say,’ Symat said. `Leave my friends alone.’

The girl quickly recovered. `You can’t order us around. And you can’t hurt us.’

`But we can hurt you,’ said a sly-faced boy.

`Projections can’t hurt a human.’

`Oh, yes, we can,’ said the boy. `We can come to you in the night. We can hide in walls, in your clothes, even in your body, human. You’ll never sleep again.’

The girl said, `You don’t have to be real to inflict pain. We’ve learned that in the years we’ve been out here. We will haunt you.’

Chem was crying. `Please, Symat, don’t let them hurt us.’

Symat stood, hesitant. The out-of-control Virtuals’ threats filled him with dread. And this wasn’t his fight; after all he hadn’t met Mela and the boys before yesterday. But Mela’s eyes were on him. His fists clenched again, he stepped forward. `Leave them alone or-‘

The girl ran at him, burst through his chest, and pushed her hands through his skull so the insides of his eyeballs exploded with light. `Or what? What will you do, human?’

But the others didn’t follow her lead.

`Kiri,’ the sly boy said. `Look at him.’

The girl turned, looked at Symat - and then stepped back, her mouth dropping.

Symat found himself surrounded by a circle of staring children. Even Mela and the boys were gazing at him wide-eyed. He saw that their protocol respect was weakening; some of them drifted up from the floor, and others tilted sideways, reaching impossible angles. They were like floating spectres, not children. They began to whisper, the strange, rapid speech he had heard from the boys in the night; he heard them mutter that strange name again - `the Guardians’.

And somehow Symat sensed the circle of scrutiny expanding beyond the limited circle of these children. After all, he reminded himself, these Virtuals were merely manifestations of the Mist, the cloud of artificial sentience in which all of Mars was immersed - and suddenly he was the centre of attention.

He had no idea what was happening, but he ought to make use of it. He raised his arms. `Get away!’

The strange children turned and fled, leaving the two boys weeping on the ground.

Mela and Symat ran to them. Mela hugged them. Chem looked up at Symat, tears streaking down his face. `Don’t leave me again, Symat. Keep me safe until my parents come back for me. Oh, keep me safe!’

`I promise,’ Symat said helplessly.

They left the town and walked on, following the canal, ever westward. The sun inched higher, showing more of its bloated red belly, and the air grew steadily warmer. The water in the canal was thick and sluggish now, and deep red-brown with sediment.

Symat was walking out of the twilight band and into the hemisphere of permanent daylight.

The Virtuals followed. The boys, subdued, stayed closer to Symat and Mela. They didn’t complain, though Symat could see they were getting as hot and tired as he was. Their bodies apparently responded appropriately to the weather, one bit of protocol they couldn’t violate.

`So,’ he said to Mela. `Bloodsuckers?’

`It’s what we call them. A lot of the kids are too young to understand the truth.’

`Which is? …’

The bloodsuckers had learned to steal something far more precious to any Virtual than blood: processor time.

`The Mist’s capacity is huge, but it’s finite,’ Mela said. `There are rules that unnecessary programmes are eventually shut down.’

`Unnecessary like abandoned Virtual children?’

`Yes. But the bloodsuckers have learned a way to, um, integrate you into their own programming. That way they co-opt your ration of processor capacity.’

`And live longer.’

`That’s the idea.’

Symat was stunned. Living in a city still occupied by humans, Virtuals had always been peripheral to him. He had no idea that this kind of cannibalistic savagery was going on among them, out of sight of mankind. `So that’s why you hid from me.’

Mela shrugged. `We didn’t know if you were a Virtual or not.’

`Not until you got stuck in the water,’ Tod said, and Chem laughed.

What else didn’t he know? `Mela - when I was trying to sleep, I heard the boys muttering. Something about Guardians. And in the middle of the fight back there, you all looked at me strangely. I heard that name again. Guardians.’ He looked at her uncertainly. `What’s going on?’

Mela flexed her hand, and held it up to the sun, as if trying to look through it. `You understand that we Virtuals are individuals. But we are all projections, from the Mist, and of wider artificial minds beyond even that. So we aren’t like you, Symat. We’re - blurred. It’s hard to explain …’

Mela was a projection of a mass artificial mind that, loosely integrated, spanned Mars, and what was left of Sol system - indeed, once it had spanned much of the Galaxy. Mars’s Mist was just part of it. This interplanetary colloquium of minds, meshed together in an endless conversation, called itself the `Conclave’, Mela told him. And sometimes she and the other Virtuals could sense the deeper thoughts of that mind, the vast undercurrents of its consciousness.

How strange she was, Symat realised as she spoke, strange in layers. She looked like a rather serious twelve-year-old girl; most of the time she acted that way. But she was old - far older than him, centuries old. She had been twelve all that time, looking after these other ageless children. And behind her, looking at him through her eyes, were misty ranks of ancient artificial minds.

`And the Conclave,’ she said, `is very aware of you, Symat.’

`Me? I’m not important. I’m just a kid.’

`Apparently you’re more than that.’

The water had almost run dry. Reefs of baking mud clogged the basin of the canal.

They slowed to a halt, and stood in a glum group.

`We’re past the point where the recycling pumps take back the water,’ Mela said. `Nobody tries to grow things further west than this any more. It’s too hot and dry. And every year this point is pulled further back.’ She looked up at Symat. `So we can’t go on.’

`Look.’ Tod pointed at the bare ground, a hundred paces from the canal. `There’s a flitter.’

Symat shielded his eyes from the sun to see.

Mela said, `It’s your parents, isn’t it? They’ve waited for you here, where you could walk no further.’

`I have to face them,’ Symat said grimly. `Maybe now they’ll take me seriously.’

Another Virtual coalesced out of the dusty air. It was Symat’s mother, grave, soberly dressed. Symat was astonished to see the streaks of tears under her eyes. `Come home, son,’ she said. `We’re here. In the flesh, in our flitter. We’ve come for you. Please come back.’ She didn’t even seem to see the Virtual children with him.

Impulsively Symat opened his arms. `I’ve made friends. Let me take them back with me.’

`That’s impossible.’

`One, then. Let me take one.’

His mother glanced sideways; Symat imagined her looking at his father back in the family flitter, listening to that gravelly voice. Give him a victory. What does it matter?

`Very well,’ his mother said. `Which one?’

Symat turned to Mela. `Come with me.’

She hesitated. `What about the boys?’

`I think I need your help.’

She looked at him, and again he had an odd sense that she knew more about him than he knew himself, that other minds watched him through her eyes. `Maybe you do.’

`No!’ Chem grabbed Mela. `Don’t leave us!’

Symat could see she was torn. `I’ll come back,’ she said. `This could be important. Just stay out of the way of the bloodsuckers and you’ll be fine.’

Symat’s mother put her own Virtual arm around Mela. `Come, dear.’ They started walking across the sand towards the flitter.

Chem, desperate, called after Symat, `You promised you’d stay, you promised you’d keep us alive.’

`I’ll come back.’

`They always say that. You won’t. You won’t! …’

Symat followed Mela and his mother, his heart breaking.

II

The flitter arrowed with perfect accuracy towards Kahra, capital city of Mars, where Symat had grown up. The ease of the journey was galling, after Symat’s slog on foot through the echoing deserts.

And as the flitter dipped low over the rooftops of Kahra, he saw lines of people snaking towards the transfer booths. The human population of Mars was passively draining into another universe. Symat glanced at his father, wondering if this part of the flight had been set up deliberately to show him the booths and the patient lines, to make a point. Hektor returned his gaze, impassive.

Symat’s parents’ villa, on the outskirts of Kahra, was spacious, airy. Mela and Symat wandered through it. The glass walls shone like fire in the light of the sun. Even after a million years on Mars some deep instinct made you aware that this tall, open design would have been impossible on heavy Earth, and the place felt all the more remarkable.

`It’s beautiful,’ Mela said.

After his abortive adventure Symat wanted to puncture her awe. `It isn’t so special. There are much grander buildings than this, all over Kahra, in fact all around the twilight belt. All empty,’ he said harshly. `You can just walk in and take whatever you want.’

`But this is home, to you. That’s the most important thing about it.’

`I don’t like being here.’

`But you don’t have anywhere else to go. You’re all stuck here together, you and your family.’

He studied her. `You’re very smart about this stuff. Perceptive.’

`You think I’m too smart.’ Just briefly her projected image seemed to waver.

Symal felt angry. Why did he have to make friends with a weird, superhuman two-hundred-year-old Virtual? Couldn’t he just have found somebody normal? `You’re not even here, are you? Not really. You’re just a projection of some vast cobwebby thing.’

`I’m here.’ She tapped her head. `It’s just that I hear things. I can’t help it. I’ll go away, if you like.’

`No.’ It had been a long time since anybody else of Symat’s age had come here. There had been few children around to begin with, and all his childhood companions had long since followed their parents into the booths. He couldn’t bear the thought of being left alone again. `You’ll have to do,’ he said.

She seemed to understand; she nodded.

They completed a circuit of the villa and found Symat’s parents. Hektor and Pelle sat in the grandest of the villa’s living rooms, while a small, silent bot, glass-hulled in sympathy with the architecture, laid out food and drink on a table.

Hektor stayed seated, but Pelle, Symat’s mother, stood up, a hopeful smile on her lips. `You two. Come and sit down. Are you still hungry?’ She waved her hand over the table; some of the dishes shimmered and broke up. `We have something for you too, Mela.’

Mela smiled. `Thank you.’ She selected a seat and, cautiously, sat down. The smart environment gave her a surface that matched the real-world seat flawlessly. She reached forward, picked a piece of fruit, and began to eat.

Symat sat too. Back home, he felt as if he had been reduced to a child once more. But it was obvious his mother, at least, was making an effort to reach him; she was even being considerate to Mela. And somehow with Mela here it wouldn’t have been right to show his resentment. So he accepted a drink.

As he had grown, Symat had often felt uncomfortable around his parents. They were so different from him, both tall and slender, matching the architecture of their Martian villa, while Symat was dumpy, squat, thick-set. Today Pelle was casually dressed, but Hektor wore the orange robe of a scholar, and his head was shaven. Both Symat’s parents had dedicated their long lives to archiving the human past on Mars, participating in a community act of remembrance to be completed before the final transfer through the booths. But in this domestic environment the robe made Hektor look formal, severe, the contrast with his son only more accentuated.

When he spoke, however, Hektor’s tone was mild. `So where do we go from here?’

`We just want to know what you’re feeling,’ Pelle said to Symat. `What made you-‘ She faltered.

`Run away?’

`You don’t have to say sorry, son. We just want to understand. ‘

His father leaned forward. `What I want to know is, where did you think you were going? You know your geography. There’s nowhere to go.’

Pelle snapped, `Hektor. He’s fourteen years old. What kind of plans do you expect him to make?’

Hektor said, `This is all about the booths, isn’t it? Everybody else goes through happily enough. All your little friends have gone.’ He ticked off names on his fingers. `Jann. C’peel. Moro-‘

`I don’t want to go into a booth,’ Symat said testily.

As always his father seemed genuinely mystified. `Why not?’

Symat waved a hand at the shining glass walls. `Because this is my home. My world. My universe! I hardly know anything about it. Why would I want to walk into nothing?’

`Not nothing,’ Hektor said. `A pocket universe, connected to our own by an umbilical of-‘

`Symat,’ his mother cut in, `I wouldn’t change a hair on your head. Don’t ever think that, not ever. But I want what’s best for you. And this-it’s as if you are refusing medical treatment, say. We can’t just ignore it. Believe me, going into a booth would be the best choice - the Xeelee are coming - in the long run it’s the only choice.’

`I think that’s the trouble,’ Mela put in brightly. `The trouble is he doesn’t believe you.’

Hektor snarled, `Who asked you, Virtual?’

Mela flinched.

Pelle held up her hand. `No. She’s right. Symat, we’ve always tried to educate you. But on some level we’ve failed.’ She seemed to be coming to a rehearsed suggestion. `So let us show you. Give us one day, that’s all. Just listen, watch, for one day. Try to see things from our point of view. And then you can see how you feel about the booths.’

Symat hesitated. `What if I still don’t want to do it?’

`Then we won’t force you,’ his mother said.

`In fact we can’t,’ Hektor said stiffly. `That’s the law. But you need to understand that we’re going through the booths, with or without you. After that you can do what you want. Stay here. Move away. There are others who choose not to come. Other oddballs and deadbeats-‘

`Just give us one day,’ Pelle said firmly.

Symat glanced at Mela. She nodded. `All right,’ he said.

Hektor stood up. `Then let’s not waste any more time.’ He spoke to the air. `Ready the flitter. We leave in five minutes.’ He clapped his hands, and the bot began to clear away the barely touched food.

Pelle patted Symat’s arm. `Don’t worry,’ she said. `We can always eat on the ship-‘

The flitter rose from Mars like a stone thrown from a crimson bowl. The little craft tumbled slowly as it climbed, sparkling. Mela peered out of the flitter’s transparent hull, wide-eyed; evidently she had never seen the world like this.

From here you could clearly see how Mars was divided into two hemispheres, barren landscapes of hot and cold, separated by a narrow belt of endless twilight. The canals, shining blue-black, laced across this precious strip. Kahra, a capital city almost as old as man’s occupation of Mars itself, was a green jewel that glimmered on the desert skin of the planet.

Looking down now, it struck Symat for the first time that Kahra was set slap in the middle of the twilight band, exactly poised between dark and light. But he knew that when Kahra had been founded Mars had still spun on its axis. He wondered if that positioning was a happy accident - or if the slowing rotation of Mars had somehow been managed so that Kahra ended up exactly where it needed to be. He had no idea how you might control the spin of a whole world, but then, it was said, the people of the past had had powers beyond the imagination of anybody now alive.

As the flitter swept through its rapid suborbital hop, the sun rose. Bloated, surrounded by a churning corona, the sun’s scarlet face was pocked by immense spots. Symat’s father had told him that the whole of the sun was a battleground between forces beyond human control, and from here it looked like it.

The flitter swooped down towards Dayside, the sunlit face of Mars. On blasted crimson rock cities still glittered. But there was no sign of life, no movement in the cities, and the canals were bone dry.

Hektor said, `Look down there. Nothing left but bugs in the deep rocks. Everything that can burn in those cities has gone already. Son, if you transplanted our villa down there it would turn into a shining puddle of melted glass. And it’s getting worse.’

`Because the sun is still heating up.’

`So it is. There is nothing we can do to reverse this. Soon the twilight belt will close, squeezed between hot and cold, and Mars will be uninhabitable, just as it was before humans came and terraformed it. And the last of us will have to leave, or die.’

This desolate prospect filled Symat with gloom, which it was in his nature to resist. `It might not come to that. What if the sun cools again?’

Pelle touched Symat’s arm. `It won’t. Those who are destroying the sun won’t allow it.’

To swell into a giant would have been the sun’s eventual fate, but not for billions of years yet. This premature destabilisation of the sun was deliberate. Creatures, malevolent and relentless, swarmed in its core, puddling the fusion processes there, and so compressing aeons of a stellar lifetime into mere megayears. And Sol was not the only star being smothered in its own heat. You only had to look around the sky, littered with red stars, to see that. `But it’s not personal,’ a teacher had told Symat once, with black humour. `The photino birds in the heart of the sun probably don’t even know we humans exist …’

`The sun is dying,’ Hektor said with bleak finality, `and Mars is dying with it, and there isn’t a thing we can do about it. And then there’s the Scourge.’

This was the trap of history, closing in Symat’s lifetime. For even as one agency was murdering the sun, another, the Xeelee, was driving mankind back from the stars.

`We were left with nowhere to go,’ Hektor said. `Until we discovered the booths.’

Symat said suspiciously, `Discovered? ‘

`Yes, discovered. You didn’t imagine they are a human invention?’

Symat supposed he had, but he had never thought hard about it. Besides, it just wasn’t something you talked about.

A few generations back, the booths had simply appeared at scattered locations, studded around the cities and parks of mankind’s remaining worlds. Their operation was simple, the execution awe-inspiring. If you walked through a booth, you would be transported, not just to another place as if this was some fancy teleport system, but to another universe: a pocket universe, as the cosmologists called it, a fold in the fabric of spacetime stitched to the parent by a wormhole-like umbilical. You could walk between universes with your luggage on your back and your child in your arms. And once you were through you would be safe, preserved from Xeelee and photino bird interventions alike.

Nobody was clear exactly how this common knowledge about the booths had reached the human population. Certainly not from the booths themselves, which were one way: nobody came back to tell the tale of what was on the other side. The folk wisdom just seemed to be there, suddenly, in the databases, in the air. But it was believed widely enough for a steadily increasing fraction of humanity to trust their own futures and their children’s to this strange exit.

Hektor said, `Obviously there has been speculation. The booths could be an ancient human design, I suppose; who can say what was once possible? Or they could come from some alien culture, though our habit of enslaving, assimilating or eliminating most aliens we came across might seem to argue against that.’ He said conspiratorially, `Perhaps it was the Xeelee themselves. What do you think about that? Our greatest foe, eradicating us from the universe - and yet giving us a bolt-hole in the process.’

`And this is what you want me to walk into,’ Symat said.

Hektor said stiffly, `We can’t tell you anything we haven’t told you a dozen, fifty times before. Somehow it never stuck with you, the way it did with other children.’

`But I thought that if we showed you,’ Pelle said, `showed you the world, the sky, the state of things, then it might make things clearer.’

`Clearer? But walking into a booth is like dying. You can’t come back. And you don’t know what’s on the other side, because nobody ever came back to tell us. Just like dying.’

`Here we go again,’ Hektor growled. `Pelle, I told you this was a waste of time. We’ve had conversations like this since he was five years old, and every time it finishes up the same. Us being reasonable, him getting angry and stubborn.’

Symat and Pelle spoke at once. `And you think that’s my fault?’ `Hektor, please-‘

Unexpectedly Mela stepped forward. She said gravely, `No wonder you argue. You’re starting out from different premises. Different positions. You’re different kinds of people.’

Hektor’s eyes narrowed.

`What do you mean, different?’ Pelle said. `He’s my son. How different can he be?’

`The Scourge has been continuing now for three hundred thousand years. To the Xeelee the Scourge is a conscious project. To humans it has become our environment.’ Mela’s voice was neutral, her words not quite her own, Symat thought. `A steady force applied to a population for long enough becomes a selection pressure. In such an environment those able psychologically to accept the reality of inevitable defeat will prosper. And that is why you are prepared to walk trustingly into the booths, even without knowing what lies beyond. Your ancestors have learned to accept similar bolt-holes without question, far back into your history. You’ve been preadapted to accept the booths for ten thousand generations! Perhaps even that was part of the grand design of the Scourge.’

Hektor said, `You’ve got a wide perspective for a twelve-year-old. ‘

Symat, troubled, thought he glimpsed the Conclave, the vast composite mind for which Mela was sometimes, it seemed, a mouthpiece. `She’s right, though, isn’t she? But why can’t I just walk into the booths with the rest?’

`Because you’re different,’ Mela said, sounding almost amused. `Can’t you see that? You don’t even look the same.’

Symat glanced around at his family, his tall, elegant, long-boned Martian parents towering over his own squat, thick-boned form.

Mela said, almost mischievously, `The differences go all the way down to the genes. You could almost be called a throw-back, Symat. But you know what? You’re just as you’re meant to be.’

Pelle snapped, `What are you talking about?

Symat demanded, `Who meant me to be this way?’

Hektor turned on the girl. `You’re getting on my nerves. Why are you here?’

Mela seemed upset by the family’s brief unity in hostility to her, but she quickly recovered. Symat thought it was as if new data were continually being downloaded into her head. `Symat, you don’t want to follow your parents into the booths. The trouble is you can’t imagine an alternative. But there is another way out.’

`There is?’

`It depends on you. The Conclave wanted to reach you, Symat. That’s why I’m here. If you hadn’t found me, it would have been somebody else. Another Virtual. There is somebody who would like to meet you. Very much indeed.’

She no longer sounded like a twelve-year-old girl at all. Looking into her eyes, Symat began to feel frightened. In the corner of his eye he saw his mother, distressed, cling to Hektor’s arm.

`Where will I have to go?’

`Far from Mars …’ Mela smiled, suddenly herself again. `Isn’t it exciting?’

III

Pelle insisted they loan her son the family flitter for his jaunt: `At least it will keep him safe.’ With very bad grace, Hektor agreed.

So Symat and Mela climbed aboard the ship once more, just the two of them. The flitter rose until the world shrank to a scrap of floor. Symat felt as if he had climbed to the top of a pole a million kilometres tall, and vertigo crowded his mind.

A Virtual of his mother’s face appeared before him, concerned. `We have to hand the ship over to the Mist,’ she said.

Up to this point the ship had been under the override of his parents, down on Mars. But now the lofty agencies who had summoned Symat through Mela would take control of the flitter and guide him into the darkness, out of his parents’ protection.

`You don’t have to go, you know,’ Virtual Pelle said in a rush. She glanced at Mela with a trace of malevolence. `You don’t have to do what she says. And you won’t - oh, you won’t lose face if you turn around and come back to us.’

`Mother, I’m caught up in some kind of mystery. I need to understand. I’m making an adult choice. I think.’

She nodded, her lips tight. `Then I won’t stop you. But I’ll be tracking you every step of the way.’ The Virtual shut itself down, dispersing in a cloud of pixels.

The ship flipped over, and Mars squirted away.

Mela was watching him. `Are you OK?’

Symat felt a pang of regret. But he had made his choice, and now he had to follow it through. `I’m fine. What about you?’

`I don’t matter.’

`Yes, you do.’

`I’m all right.’

He tried to focus on the journey. Mars was gone, and the sun’s huge hull was receding. `We’re going away from the sun. Where to? Saturn?’ His knowledge of Sol system’s geography was vague, but he knew Saturn was a giant world out in the dark, far out beyond the orbit of Mars.

`Not as far as that. Not at first.’ Her small face was creased with concentration. It was as if she was listening to a faint voice only she could hear.

`So where? Jupiter?’

`No. Jupiter’s on the far side of the sun right now.’

Symat was faintly disappointed. He’d have liked to see the black hole remnant and its shattered moons. `Then what? An asteroid? There is a belt of asteroids between Mars and Jupiter.’

`There was. But the belt was mined out long ago. And then when the sun started heating up many of the remaining icy bodies were destroyed. Sol system was a lot more interesting, once.’ She sounded wistful.

`So where are we going?’

She smiled. `You’ll see.’

He studied her, curious. `What’s it like?’

`What?’

`When you get stuff downloaded into your head.’

She frowned, trying to find words. `It’s as if I lost my memory, then recovered it.’

`It doesn’t sound very comfortable. Not if it feels like you’re sick.’

She sighed. `It’s not comfortable. And I don’t have any control over it. The stuff just pours into my head when it’s needed - when you need it. Sometimes even when I’m asleep, it comes.’

`I didn’t know your kind slept,’ he said. She looked hurt, and he added hastily, `Sorry. And I’m sorry you’re having to put up with this, for my sake.’

`It’s not your fault. And anyhow if I hadn’t been around when the Conclave decided it needed to speak to you, if they’d picked some other Virtual, I’d never have got to see all this.’ She waved a hand at the utter darkness beyond the enclosing walls of the flitter, and they both burst out laughing.

Symat clapped his hands to opaque the hull, and suddenly the flitter felt like a cosy room. `So shall we play a game?’

Mela smiled. `OK.’

No longer children but not yet adults, the two of them ran and laughed through the confines of the tiny ship, as it sailed on into the mined-out emptiness of Sol system.

After a day of silent transit, their destination came swimming out of the dark.

It was just a lump of ice at first glance, maybe a couple of hundred kilometres across. Tinted an odd red-purple colour, it was only vaguely spherical. It was impossible to tell if the scars on its surface were natural or man-made, for the ice had obviously been heavily melted, and the ridges and crater walls were softened and slumped. But this island of ice was occupied. Symat saw lights, defiant green and white, gleaming in crater shadows.

And as the flitter skimmed low a spindly tower, kilometres tall, loomed above the crumpled horizon. It was absurdly out of proportion on this little world. When he looked carefully Symat saw a ghostly purple bloom at the top of the tower: rocket exhaust.

Even given the tower, this worldlet was hardly spectacular. But he had to admit he was impressed when Mela finally told him the name of this place. It was Port Sol.

`That’s impossible,’ Symat said immediately. `Port Sol is a Kuiper object.’ An ice moon, one of a vast flock drifting far beyond the orbit of the farthest planets. `We’re inside the orbit of Saturn. What’s it doing here?’

A Virtual popped into existence in the middle of the cabin. `I think I can answer that.’ It was a man, perhaps as old as Symat’s father, though it was hard to tell physical ages. But unlike Hektor he was short, squat, his limbs short and his belly large.

Symat resented this sudden intrusion. He snapped, `Who are you?’

`Actually I don’t have a name. You can call me by my role, which is the Curator.’ Despite his persistent grin he looked like a curator. He was bald, and he wore an antique-looking robe, black, sweeping to the floor, its breast adorned with a green tetrahedral sigil.

Mela asked, `Curator of what?’

`Why, of Port Sol, of course. One of mankind’s most precious bastions - and still a working place today.’

Symat said, `But Port Sol isn’t in the Kuiper Belt any more.’

`No indeed. Now it swoops around a long elliptical path that reaches from Saturn all the way in to Earth’s orbit. It has been brought in from the dark, along with a whole flock of other outer-system objects. All for a purpose.’

`Why are you so fat?’ Mela asked bluntly.

The Curator patted his belly, apparently not offended. `Do say what’s on your mind, child! In the cold, the rounder your shape is the better off you are. Ask a Silver Ghost! And out where Port Sol came from, believe me, it’s cold, even now. You’re Mela, aren’t you? There has been a lot of gossip in the Conclave about you. Metaphorically speaking, of course. You’re doing a good job. A lot of us are jealous.’ He reached out and ruffled Mela’s short-cut hair. She flinched back, glaring.

Symat said heavily, `Can’t you tell she doesn’t like that?’

`Actually, no. I’m a little light on sentience programming. In the empathy area, in fact. Though I hope that what I lack in personality I make up for in charm. Of course I could be wrong about that. But how would I ever know?’ He laughed lightly.

Mela stared at him. `How can you be like that? Don’t you want more, to be whole?’

`Not really. Believe me, when you see the job I have to do, you’ll understand why.’ Even now he kept smiling. `Welcome to Port Sol!’

Under the Curator’s effortless control, the flitter dipped and swooped over Port Sol’s eroded landmarks.

Every child in the system knew about Port Sol. It was itself ancient, a fragment of unprocessed rubble left over from the formation of Sol system. And its human history stretched far back too, almost as far back as man’s first tentative steps off the home planet.

`Once they built starships here,’ the Curator said. `Before hyperdrive, even. They used the worldlet’s own water ice for reaction mass, digging out great pits like that one.’ The quarry he pointed out was a slumped hole in the ground, indistinguishable from a thousand others. `When hyperdrive came this place was bypassed for a while. But then, because it was so hidden away and forgotten, the first of the Ascendents came here.’

`Ascendents?’ Symat asked.

`Undying,’ Mela said immediately.

The Curator raised a thin eyebrow. `They’ve been called many names in their long history - jasofts, pharaohs - few of them complimentary. Ascendents isn’t so bad, I think: we are all their descendants after all … Whatever they’re called, I care for them. That’s my vocation! You’ll see, anyhow. You’ll meet them. They want to meet you, Symat.’

Symat tried to absorb that, and tried not to react to Mela’s obvious fear.

The flitter circled this little world rapidly, and soon they once more approached the mast, with the flare of blue light at its tip. Buildings clustered at the base of the tower, while machines like giant beetles dug a pit in the ice that sliced through the pale marks of older workings.

Symat said, `This is a rocket, isn’t it? And it’s pushing this moon.’

The Curator nodded. `Very perceptive. We’re actually at one spin pole of the moon - a good place to push.’ He pointed. `The engines are GUTdrives - one of mankind’s oldest technologies, immensely reliable. The exhaust is plasma, charged matter, the outflow shaped by magnetic fields. And, just like in those ancient starship engines, the stuff of Port Sol itself is being consumed as reaction mass. You can see how the engineering here has churned up the old surface. Aside from Earth itself, Port Sol is probably the system’s key historic site. But Ascendents care little for archaeology.’ He sighed. `I suppose you wouldn’t if you could remember it all!’

Mela said, `So this is an Ascendent project.’

`Well, of course. The mass of Port Sol is huge, and by comparison the rocket delivers only a small push. You have to keep shoving for a very long time before you can kick it out of its orbit. But that’s just the sort of long-term, dogged programme the Ascendents excel at.’

The rocket tower dropped behind the horizon, and the flitter swept down towards a plain of ice, heavily melted by the heat of multiple landings. Nearby was a cluster of domes, evidently their destination.

As the ground fled beneath the descending flitter, Symat spotted a slim black pillar, obviously artificial, standing in the middle of what looked oddly like a forest, `trees’ sculpted from ice. `Look, Mela. A transfer booth! Even here they are escaping.’

The Curator looked surprised. `Oh, that’s not for people. Did you imagine booths are just for humans?’ He told them that when Port Sol had first been discovered it had an indigenous fauna, slow-moving inhabitants of the deep cold with liquid helium for blood. `Once we farmed them; we transplanted them to other cold worlds. Somehow they survived a million years of cohabitation with mankind - even the dreadful summer we have brought to Port Sol by pushing it into the heart of the system. And now a booth has appeared, right in the middle of their Forest of Ancestors, and, with our help, the Toolmakers, the ones in their motile phase, are passing through to their own destiny. A slow process, I can tell you …’ He seemed surprised at their incomprehension. `There are many life forms in Sol system - or were, before we came along - but even now many of them survive. And as far as we can tell, every one of them with the remotest level of advancement has been supplied with booths so they can escape the destruction of the sun. Touching, isn’t it? And not only that, there are suggestions in the records that other species, driven to extinction long ago, have been provided with similar escape routes. The Silver Ghosts, for example … The booths are evidently part of a long-term rescue strategy, by whoever is responsible. It could be the Xeelee,’ he mused. `Some say it is. The Xeelee relish the diversity of life, and seek to protect it, even when it snaps at them, as we have …’

The silvered domes at the base of the rocket tower turned out to be the upper levels of much more extensive structures, buried deep under the ice.

The Curator took them down through a hatch in the bottom of the flitter, through a kind of airlock, and then into the interior of the base. They never walked in the vacuum, out on the ice. Symat, who had never walked anywhere you would need a pressure suit, was faintly disappointed to lose out on a little bit of adventure.

The Curator led them along cold, echoing corridors, past closed-off rooms. Just as on Mars there were few people here, it seemed. Symat was getting a sense of Sol system as a series of empty planets and moons, like dusty rooms in a deserted house.

The Curator asked if they wanted to rest or eat, but they were both too excited, or apprehensive. The Curator gave in with a cheerful shrug. `Then I’ll take you to the Ascendents.’

He led them along more corridors until they came to a brightly lit area, a complex of corridors that stank strongly of antisepsis, like a hospital. The Curator paused at a door. `Now before you go in,’ he told Symat, `try not to be afraid.’

Symat said testily, `Let’s get on with it.’ He wasn’t about to hesitate in front of Mela. He stepped forward boldly. The door slid aside.

He entered a low, wide room, white-walled, flooded with pale light. There were beds here - no, they were more like medical stations; each had boxes of equipment hovering in the air beside it. Bots cleaned the walls and ferried supplies. He saw no human attendants, but there were many Virtuals who nodded at the Curator. Rotund individuals like him, they all seemed to have broad faces and wide smiles.

Symat inspected a station more closely. A bot hovered suspiciously, but he wasn’t impeded. The station was a pallet covered by a translucent bubble. It was marked with a number: 247, in bold digits. Inside the bubble, lying on the pallet, was a man. His limbs like sticks, his belly imploded, and with tiny bots crawling over his body, he looked more dead than alive. But as Symat cast a shadow over his face, that skull-like head turned. Symat shuddered and stepped back.

They walked on, between the rows of stations. The floor was soft and Symat’s footsteps made no sound.

The Curator said, `They are unimaginably old, some of them - and several of them, with no real memory of their own deepest past, don’t even know how old they are themselves. The best way to date them is actually through the anti-ageing technology embedded in their bodies. But even that is unreliable.’

As they passed, the naked Ascendents stirred and whispered, dry skin rustling.

`We’re disturbing them,’ Mela said softly.

`Don’t worry about it. They are creatures of routine - as are we all, but in them it is taken to an extreme. And anything that disturbs that routine disturbs them. That’s why only bots and Virtuals are used as attendants. You don’t want to frighten them with a new face every century or so!’

Symat wondered how old the Curator himself was.

One old woman, to Symat’s astonishment, was out of bed. She was naked, her skin so flaccid she looked as if she had melted, and tubes snaked out of all her orifices. But she managed to walk to a cabinet a few paces from her bed, where, with a trembling hand, she picked out fragments of food that she pushed into a toothless mouth.

`She likes to feed herself,’ the Curator said. `Or at least to believe she does. It’s good for her to have some independence. But look here.’

The floor was cut through by a deep rut, hard metal and ceramic worn away by this old woman’s soft feet. And where she had lain in her bed she had left the shape of her body compressed into the mattress.

The Curator said dryly, `Perhaps you can see why many of us working in this place prefer to forgo personality. It’s better not to think about it. Better still not to be able to think …’

The stations were set out in orderly rows, a neat rectangular grid. Symat counted no more than twenty or twenty-five rows in each direction: there were only a few hundred Ascendents here.

The Curator seemed to know what he was thinking. `Four hundred and thirty-seven. If you’d come here a decade ago there were four hundred and thirty-eight.’

Mela asked, `This is all?’

`As a group they have been ineradicable. They have time on their side: that’s what you always have to remember about Ascendents. If you try to get rid of them, no matter how strong you are, all they have to do is wait for you to grow old and die, and for your children and grandchildren to die too, wait until you’re nothing but a sliver of data in a history text, and then they just walk back in.’

`They are dying out, though.’

The Curator shrugged. `Nobody is making immortals any more. And entropy catches up with us all in the end. But despite their strangeness, they are mankind’s treasures.’

Mela asked, `Why do you say that?’

`For all they have seen,’ the Curator said. `For the wisdom they have accrued, when you can dig it out of them. And for all they have done for us - and continue to do. It was the undying who founded the Transcendence, who tried to bring us to a new plane of being altogether. They ultimately failed, but what a magnificent ambition!’

`And you say they still work for us?’ Mela asked.

`By moving Port Sol,’ Symat saw immediately.

`Yes,’ the Curator said, `But what they have done is rather more spectacular than pushing around a mere ice moon! You see, long ago, the undying resolved to move the Earth itself …’

It was the sun, of course.

As the downpour of solar radiation grew too intense, Earth’s natural processes couldn’t be sustained. And when the swelling sun’s photosphere washed over it like a misty tide, would Earth be sterilised, scorched, melted, even vaporised? It would take a long time, hundreds of thousands of years, before Earth was destroyed entirely. But Ascendents fretted on long timescales. You could say that was the point of their existence.

How do you save a world from an overheating sun? Mankind had never had the power to tinker with the processes of stars themselves. Could you shield the world with mirrors and parasols lofted into space? But any such shield would eventually be overwhelmed as the sun expanded. There was only one option: to move the Earth itself. But how?

You could push it. You could mount a giant rocket on a spin pole, as had been done on Port Sol, or even a series of rockets around the equator. But you would consume an immense amount of Earth’s own matter in the process, and any instability could cause the planet’s crust to shake itself to pieces. You might end up doing more harm than good.

Alternatively you could use gravity. If the Earth still had its Moon, you could have used that as a tug: push away the Moon as violently as you liked, and let lunar gravity gradually haul the Earth on a slow spiral away from the sun. But the Moon had been detached from the Earth in the course of a long-forgotten war.

Or you could do it piecemeal.

The Ascendents mounted venerable GUTdrive engines on a whole fleet of Kuiper Belt ice moons, including their own base, Port Sol. It took a long time for the slow push of the plasma rockets to make a difference, but at last the moons came swooping out of the dark into the inner system, entering complicated orbits that shuttled between Earth and the greatest planets, Jupiter and Saturn.

And with each moon’s passage Earth’s orbit was deflected, just slightly.

With a long series of slingshots Earth was gradually nudged outward from the sun, while the giants were subtly moved closer. It was as if the Ascendents had linked Earth to its giant cousins with immensely long chains, that drew them slowly together. It was going to take a million encounters with moons the size of Port Sol to move the Earth out to its destination, a new orbit around Saturn. At the rate of two or three encounters a year that would require thousands of centuries. But the undying always had time in abundance, time and patience. And Earth was on its way.

It was a typical undying project, on immense timescales, but low-tech. But you had to keep a sense of perspective, Symat thought. Where the Xeelee had blocked the light of suns across a supercluster of galaxies, all humans could manage was to nudge one little world across Sol system.

And in the end even this monumental exercise in persistence hadn’t been enough. The immortals had saved Earth from the expansion of its sun. Now the Xeelee had come to Sol system, and a new danger loomed.

But again, it seemed, the undying had been preparing.

The three of them continued to walk among the ranks of immortals, each in her station, each with her number.

As they passed the dimly stirring figures, the Curator kept smiling.

Symat asked curiously, `Why do you grin like that?’

`None of them can see well. But many of them respond to simple shapes.’

`A smiling human face,’ said Mela, wondering. `Like a baby. A baby can recognise a smiling face almost as soon as it’s born.’

`Yes. Remarkable, isn’t it? As if life is a great circle. That’s why we smile all the time.’ He tapped the green tetrahedron on his breast. `A lot of them seem comforted to see this too. We’re not sure why. It must be a very ancient symbol, of something.’

Symat asked the Curator about the medical-station numbers.

`They are for our purposes. We number them in order of age, as best we can. When one dies you have to renumber those younger - though young scarcely seems appropriate for creatures such as these! - but there are so few it isn’t a great burden.’

As they walked the age numbers fell away, below twenty, fifteen, and at last to single figures. Symat felt his heart unaccountably thump. And then the Curator brought them to a bed, where a short, slim form lay, obscured by her translucent tent. The bed was adorned by a single digit: 1.

`The oldest,’ Mela breathed.

`She has been called many names,’ the Curator said. `Leropa, Luru Parz, other variants; perhaps one of these is her original given name. If she knows she won’t tell us. She claims to know the date of her birth, but it’s so long ago we can’t reconcile her dates with current chronologies more precisely than within five thousand years … Take a good look, Symat. She is certainly the oldest human being any of us will ever see. She is probably a million years old. Think of that!’

Suddenly the woman’s eyes flickered open. Mela gasped.

Symat stepped forward, his pulse hammering in his ears. And as he came by the bed a hand like a claw shot out to grab his wrist. He forced himself not to flinch, for fear he might snap bones like dry twigs.

Her black eyes were on him. She opened a ruined mouth and whispered, `There are questions you need to ask.’

To a fourteen-year-old she was a figure from a nightmare. But her leathery palm was warm on his skin. She was old, she was very strange, but she was human, he could feel that. `I don’t know how it must be,’ he said.

`What?’

`To be like you.’

She closed her eyes briefly; he could actually hear the dry skin rustle on her eyeballs. `If you knew how many times I have been asked that … I have thought the same thoughts so often they don’t need me to think them any more. Perhaps I am a robot, then. Certainly I am no longer human, if I ever was, since the moment I took that pill given me by Gemo Cana, that murderous witch …’

`Who?’

`But that is why I am valuable, you see. I and my kind. For, long after love and hate are gone, even after meaning is lost, we keep on and on and on. And, given enough time, we achieve greatness.’

`You moved the Earth.’

`Yes. A human Galaxy was just a dream. Earth is the home of man, and as long as Earth exists, man will endure.’

`But it isn’t enough,’ Symat said.

`No. Because the Xeelee are here.’

`People are fleeing. The booths-‘

Her face, a mask of imploded skin, crumpled a little, showing disgust. `The booths. A solution for cattle bred for defeat, beaten before they are even born. Have you ever heard of Original Sin?’

`No.’

`Child, you know there is a better way. And that is why you must go to Saturn.’

His mind was reeling. `I don’t know anything about Saturn. What must I do there?’

`You will know,’ she said. She fell back on her pillow, her eyes closing, but she kept hold of his arm. `It is why I made you, after all …’

Symat, electrified, astonished, could only stare at her.

IV

Port Sol fell away into the dark. Symat and Mela were travelling ahead of the ice moon on its endless cycling trajectory between the spheres of Earth and Saturn, but where Port Sol took years to complete a single orbit, the flitter would take only days.

And now the flitter had a third passenger. The Curator wore his antique robe with its tetrahedral sigil, and his broad face was fixed with his habitual smile. But as Port Sol dwindled to a point of crimson light Symat thought he saw fear in his Virtual eyes.

It had been Mela’s idea to bring him. `You might be able to help us,’ she had told him. `You know this Luru. You might be able to figure things out.’

`I’m a Curator,’ he had protested. `I keep these human museum pieces alive. I’m not designed to interpret their mad ramblings.’ But Mela had kept on, pressing him to come.

Symat was reluctantly fascinated by this exchange. He reminded himself that they were both expressions of a much vaster interlinked awareness. As the Curator and Mela argued it was as if he was listening to the internal debate of a single mind.

They certainly weren’t human, not even Mela; Symat was the only human here. And as the darkness closed in on the ship he felt increasingly alone, and far from home.

The flitter had internal partitions you could turn opaque, and he shut himself up inside a little boxy room. He didn’t want to deal with the Curator and his resentful wittering, and he didn’t much even want to be with Mela.

After a day of this Mela asked to see him. He wouldn’t let her in, so she just walked through the walls, protocol warnings sounding. She shook her arms and flexed her fingers until all her rogue pixels had settled back into place. `That hurt.’

Symat was lying on a pallet. `Then don’t do it.’

She sat down uncertainly. `What are you doing?’

`Nothing.’ He had been reading, watching silly kids’ Virtuals, stuff he had liked years ago. Now he felt oddly self-conscious and shut it all down.

She asked, `You want to play a game?’

`No, I don’t want to play a stupid game.’

`What’s the matter with you? You’re not much fun.’

`I don’t feel like fun. I feel-‘

`What?’

`I’m sick of being pushed around. My parents wanted me to follow them into the booths. So I ran away. But then the Conclave got hold of me, through you. Now I find this stupid old woman, Luru, who says she planned me for some purpose long before I was even born. And I’ve ended up coming all the way out here, into the dark.’

`Welcome to my world,’ Mela snapped. `That’s how I feel all the time. The Curator too, probably.’

`You aren’t human.’

`But we’re sentient,’ she hit back. `Is that how you think of me, just a part of some kind of trap?’

He flinched. `I’m sorry. I didn’t mean that.’

She softened a little. `Anyway, Virtual or human, what difference does it make? Look around, Symat. Everything is old. Everything in the universe has been shaped by humans, or their enemies. Every important decision was made long ago. So we have very little choice about things. My mother used to feel the same way,’ she said, a little wistfully.

It was the first time she’d mentioned any detail of her parents. `She did?’

`She said she’d always felt like a child herself, a child who had grown up in the halls of some vast and dusty museum, where everything was frozen and on display, out of her reach … Look, Symat, if you do have some purpose, it must be important.’

`But if I’ve got no choice about any of this, what is there for me?’

She thought about that. `Dignity?’ She stood up. `Come on. Let’s go and wind up the Curator. I want to know what kind of underwear he has on under that stupid robe.’

Laughing, they left the cabin.

Saturn loomed out of the dark.

This wasn’t like approaching Port Sol. They had come swooping down on that much-engineered little worldlet in a flash. The largest surviving planet in Sol system, Saturn was majestic and stately, a misty disc painted red by the sun. Its size was obvious, oppressive.

The ship hurled itself through Saturn’s tremendous shadow. Symat saw lightning crackle purple and white across the clouds, as storms that could have engulfed the whole of Mars played themselves out. This was the power of nature, he thought, even now dwarfing humanity and its dreams. As he watched, Symat’s heart pumped in a kind of retrospective panic. To think that he might have lived and died on Mars, or even followed his parents into a booth, without seeing such wonders as this!

The flitter swooped away from Saturn, climbing up and out of its deep gravity well, the energy of its incoming trajectory dumped. And the Curator showed Symat how to look for the moons.

Spacegoing mankind had swept like a storm through Sol system, shattering in a few millennia the patient geological assemblings of aeons. Saturn’s ice moons, if not taken apart altogether, had been extensively mined. One moon was more interesting, though. The Curator called it `Titan’. Once this small world had had decks of clouds beneath which complex chemical processes had played out; humans had sent scoop-ships and trawlers to mine the air and the hydrocarbon seas. But Titan, starved of heat, had never spawned life. Now, as the sun brightened, Titan was at last stirring from its chill slumber. It was a marvellous prospect, the birth of a new world right in the middle of Sol system: even in these desolate latter days you could still find new life. But no human scientists were studying the miracles unfolding in Titan’s clouds. This was not an age for science.

They left Titan behind. And as the flitter continued to swoop around Saturn’s gravity well, the true human purpose of this system was gradually revealed.

`Can you see?’ The Curator ducked and pointed, picking out lights scattered among the moons. `And that one? They are drones. Sensor stations, weapons platforms. All sentient.’

The sky was full of them, machines that flocked like metallic birds in the ever-changing gravity field of Saturn and its moons. Some of them gathered into rings that girdled Saturn’s equator, which the Curator wistfully said were an echo of an even stranger wonder of the past, natural rings of ice and dust that had long been disrupted by war. And once you could have seen even more spectacular artefacts, the ruins of wormhole mouths, the remnant of a transit system that had once spanned a Galaxy but had collapsed with the demise of its builders, the Coalition.

But Symat understood that the beauty of the weapons clouds wasn’t their point. Their purpose was lethality. The whole of the Saturn system was a fortress. And it was all because of the Ascendents.

When the vast retreat of man had begun, even when only the most remote of colonies had yet been evacuated, the undying with their eerie far-flung prescience had planned the end game. Before the siege of Earth itself began, it would be necessary to make a stand.

Saturn had always been a military stronghold. As long ago as the Exultants’ heroic effort to win the Galactic Core, huge war machines had been buried in the planet’s deepest clouds, ready to leap to the defence of Earth if any foe dared attack the capital planet. These brooding machines, self-maintaining, self-enhancing, became known as the Guardians.

Now, as a far more formidable foe gathered, the Ascendents turned to Saturn once more. Earth itself was to be corralled with gravitation and brought out here, to circle on the rim of Saturn’s mighty gravity well, where it could be protected. And the war machines under those clouds, already powerful, were enhanced with the accumulated learning of a million years of interstellar war.

The purpose of the undying had been unswerving. But this project was not quite as under their obsessive control as they would have preferred. There was risk.

`I don’t understand,’ Mela said. `What risk?’

The Curator waved a hand, and the air was filled with a high-speed chatter of automated signals. Symat thought he picked out questions and responses, handshaking, a kind of dialogue. The Curator said, ‘The Guardians are very old. They have long since got used to making their own decisions. When a ship like this comes sliding into their space, they get very suspicious. Can’t you tell, from the way the drones are swarming around us? All that’s keeping us from being destroyed right now is our flitter’s responses to the Guardians’ continual interrogation.

`And when the Ascendents decided to move Earth here - Lethe, a whole planet sliding across Sol system - one false word and the home of mankind might have been blown to bits by machines meant to protect it.’

Symat said, `We’ve been at war with the Xeelee for a million years. What can these Guardians have that’s so powerful it could make a difference now? And why hasn’t it been thrown into the war before?’

`I think I can answer that.’ Mela’s eyes clouded, and there was a sheen about her face, a waxy unreality. She screwed up her forehead as she tried to integrate the information pouring into her head.

Long ago, as mankind advanced across a Galaxy, under a purposeful programme called the Assimilation, whole alien cultures were eradicated or subsumed, their technology and learning purloined. Most such treasures, as Symat had guessed, had been thrown into the vast war effort. But some had been secreted away by the patient undying. Insurance for the future, they thought of it.

One such was the technology called the Snowflake. It had been found in orbit around an ancient star in a globular cluster out in the Galaxy’s halo. It was a stunning artefact, a regular tetrahedron measuring over fourteen million kilometres along its edges. Humans gave it this name because like a snowflake the structure had a fractal architecture, with the tetrahedron motif repeated on all scales. And the Snowflake, it was discovered, was full of information: it was an iron-wisp web of data, a cacophony of bits endlessly dancing against the depredations of entropy.

The Snowmen, the human label for the vanished builders of this lacy monster, had an utterly alien motivation. The Snowmen decided that to record events - and only to record - was the highest calling of life. They took apart their world and rebuilt it as a monstrous data storage system. After that they watched time unravel - and waited for the universe to cool, so they could capture even more data.

Thus the Snowflake had hung in space for thirteen billion years. Then, during the Assimilation, a human ship came.

The Navy crew, intent on plunder, had been unsubtle - but their ship had been devastated by an unexpected blow, broken apart by a beam of directed gravity waves.

It had taken some time to work out what had happened, how the Snowflake had struck back.

Mela lacked the vocabulary to express the concepts downloading into her mind, and she looked at the Curator. Reluctantly, he closed his eyes, and began to speak deliberately. `There is a profound principle at work. Once it was known as the Mach principle. Mach, Marque, something like that. Every particle in the universe is linked to every other. That is why inertia exists; when you push something, the universe itself drags it back.’

Symat frowned. `What connections? Gravity?’

The Curator frowned. `That, and quantum wave functions, and, and - I can see it, I can’t say it! The ancients understood. If you use complex arithmetic to extend most theories of cosmology-‘

Symat held up his hand. `Just tell me what happened.’

`The Snowmen had a defensive system. They found a way of manipulating these cosmic linkages. A way to use them as a weapon.’

Symat barely understood enough to be amazed. `How?’

`Does it matter? I guess you learn a lot in thirteen billion years.’

Thanks to its Mach-principle weapon the Snowflake was saved from the Assimilators, that first time. But the humans returned, of course, evaded the weapon, and took what they wanted. They used the technology of the Snowflake itself in their own information-storage systems across the Galaxy.

And they took away the strange global-manipulation weapons system, but that turned out to be much harder to understand. When it didn’t yield early results it was reduced in priority, shuffled from one research centre to another, until it became so obscure, despite its potency, that a clique of undying were able to spirit it away and develop it for their own purposes.

The Curator peered at Saturn uneasily. `And that, it seems, is what is held under those clouds. A weapon of last resort.’

`But,’ said Symat, `what has this got to do with me?’

Suddenly Mela’s face worked, and the tone of her voice hoarsened. `We need you because the Guardians won’t listen to us. Is that clear enough for you?’

Symat was shocked. This time the intervention was crude, as if she had been possessed by a different personality altogether.

The Curator stepped forward and grabbed her arm, one Virtual handling another. `Ascendent. Show yourself. Leave this child alone.’

Mela spasmed, and her eyes rolled up in their sockets, showing white. She blurred briefly and broke up into a rough sculpture of blocky pixels. Then Mela stumbled backwards, reforming as she emerged from the cloud of pixels.

And from that mist of light a new figure coalesced. Suddenly there were four of them, and the flitter’s tiny cabin seemed very crowded.

004

The newcomer was a woman, dressed in a brown robe as drab as the Curator’s. Small, dark, her face was smooth - but Symat immediately saw that the smoothness was a sign of great age.

Black eyes fixed on Symat.

`Ascendent One,’ the Curator breathed.

`You can’t be Luru,’ Symat said immediately. `I saw her. She’s a dried-out skeleton. She could barely move.’

`I’m a projection,’ the new Virtual said, unfazed. `I am as she was long ago. And my sentience overlaps with hers, though time-shifted.’

The Curator sounded uneasy. `Most of the Ascendents are conscious only briefly each day. It will take Luru, the real one, a long time to live through this Virtual’s experiences. But she has time, of course.’

`Her will is mine,’ said the Virtual. `When I speak, she speaks. Remember that.’

Symat felt deeply disturbed. To see Mela split into two and give birth to this monstrous form was an unwelcome reminder of how strange all these Virtual creatures were, how inhuman - and how interconnected, their identities somehow flowing one into another. He gathered his defiance into a knot. `You told me the Guardians won’t listen to you.’

Luru eyed him. `They’ll listen to you, though.’

Symat felt the universe pivot around him, as if the Guardians’ strange cosmic weapons had been turned on him. `Me? I could command the Guardians?’

`Of course,’ she said. `That’s why we bred you.’ She stepped closer to him and he thought he could smell her, a dry scent like a musty library. `I’ll show you,’ she said. `Come to Earth.’

V

So Symat’s strange odyssey ended on Earth, the planet of his most remote ancestors.

There was an Earth in Symat’s head, mistily imagined, a world of water and life, of blue and green. It had been taken out of Mars’s sky long ago, many generations before he had been born, and sent on its way to Saturn. It wasn’t something you talked about, the loss of the home world.

But the Earth that came looming out of the outer-system cold was not like that story-book vision. The mountains were worn down, and the sea floors were rimmed by banks of salt, drained save for dark remnant puddles. The air seemed thin, supporting only wispy traces of cloud. And though a few cities still glittered, the ground of Earth shone brick red, the red of Mars, of rust and lifelessness.

`Earth has grown old,’ he said.

Luru was watching him, apparently interested in his reaction. `Old like its children.’

`It is well guarded,’ Mela murmured.

`There is nothing more precious,’ Luru said.

On its final approach to the planet the flitter cautiously descended through shells of automated sentinels, and artificial suns that swooped on low orbits, casting splashes of yellow light. Luru said that not all those satellites carried weapons. Earth’s magnetic field had failed. The sun was far away now, but the electromagnetic environment around a gas giant was ferociously energetic. Where nature failed, humans had to step in; and so devices orbited the Earth to protect it with new shields of magnetism.

The flitter ducked deep into the air, and the sky turned a muddy red-brown. Everybody stayed silent as the ground of Earth fled under the ship’s prow.

The cities were sparsely scattered, and Symat could see no logic to their positioning. Perhaps they had been placed along the banks of long-dried rivers, or at the shores of vanished oceans; the cities endured where geography had eroded away. Many of the buildings were airy confections of glass and light that wouldn’t have looked out of place on Mars. But these modern cities were fragile flowers that grew out of mighty ruins, covered by drifts of red dust.

Mela picked out patterns. `Look. Lots of those old ruins have got circles in them. See, Symat?’

She was right. Sometimes the circles were obvious, rings of foundations or low walls that could be kilometres across. In other places you could only spot the circles by the way other ruins fitted around them, filling up their interior spaces or crowding around their circumferences.

Luru’s eyes, black as night, gleamed bright as she peered out at this ancient architecture. Perhaps in these traces she saw some trace of her own long life, Symat mused.

In every city they passed over Symat spotted transfer booths. Even Earth, which Luru and her Ascendents had laboured so long to save, was draining of its people.

Wild things lived on the lands between the last cities. The flitter passed over what looked like plains of grass, even forests of stunted trees, and occasionally its passage scattered herds of animals. But there were swathes of vegetation that wasn’t even green.

The flitter at last swept over a southern continent that seemed even more worn-down than the rest, and came to rest at the outskirts of yet another city.

Symat deliberately jumped down from the hatch, falling a half-metre or so to the dusty ground. He fell slowly, though once his feet were planted in the dirt of Earth, invisible inertial systems ensured his weight felt normal to him. Gravity was indeed low here, he thought, somehow lower than Mars’s. But Earth, the mother world, had always defined the standard of gravity: how, then, could its gravity be reduced?

He looked around. The city was unprepossessing. You could clearly see the usual circular tracings, but the structures they had supported were razed to the ground. Amid these ancient foundation arcs stood only a small, shabby cluster of more recent glass buildings.

There was nobody about. The Ascendent was quiet as she wandered around the circular profile of one vanished wall.

Symat asked, `Luru, why have you brought us here?’

`I think this place means something to her,’ Mela said. She guessed, `Did you grow up here, Luru? Were you born here?’

Luru’s face remained impassive, but she nodded. `Yes, I was born here, or rather in the ruins of a still older city on this site - born in a tank, actually, for that was the way in those days.’

Symat found it hard to imagine Luru Parz ever having been young, ever being born.

`The whole of the Earth was in the grip of alien conquerors. They built this city, erasing the ruins. They called it Conurbation 5204. These circles you see were the bases of domes of blown rock. The place was beautiful, in its way. There were plenty of places to play, for me and my cadre siblings.’

`It was home,’ Mela said.

`Oh, yes. Even a prison becomes a home.’

The Curator looked at her almost with compassion. `You never told me any of this.’

`You were told what you needed to know,’ Luru said harshly. `I worked here, for an agency called the Extirpation Directorate. My job was to erase the human past. We humans were useful to our conquerors, but troublesome. To detach us from our history, to strip away our identity, was their strategy to control us.’

Symat felt disgusted. `And you did this work for them?’

`I had no choice,’ she murmured. `And the work was challenging, intellectually. To eradicate is as satisfying as to build, if you don’t think beyond the act itself. Of course we failed. Look around you!’ She laughed and spread her arms; it was a grotesque sight. `Since the great levelling of those days, more cities have been built on the foundations of the old, only to fall into ruin, over and over. History just keeps on piling up, whatever you do.’

Mela asked curiously, `Did you have children, Luru Parz?’

`Not that I knew of. If I had I wouldn’t have lived so long. There is a logic in immortality.’

`Lovers, then,’ Mela said. `You must have had lovers.’

Luru smiled. `Yes, child. One lover. But we fell out. He was a ragamuffin. He escaped the conquerors’ cities, preferring to live wild. We were on opposite sides of the argument on how to deal with the Occupation, you see. He died well, though. He died for what he believed in.’ She said this neutrally, her face blank.

Mela asked softly, `What was his name?’

Luru took a rattling breath. `Suvan. Symat Suvan.’

Symat’s mouth dropped open.

The Curator stared at him. `So now we know why you have been conjured into existence, boy.’ He laughed out loud.

The clustering artificial suns swarmed out of the sky, and night fell. There were still creatures on Earth that needed a cycling of day and night, it seemed. But the dark revealed a sky crowded with stars and weapons, with misty Saturn and swollen Sol.

Symat and his party returned to the flitter. Mela shared a cabin with Symat; she went to bed and seemed to fall asleep immediately. Symat could not settle. Too much strangeness was swirling around in his head - and nothing as disturbing as the fact that he had been named after the lover of an Ascendent, a man dead a million years.

When light began to seep into the sky, he slid out of the cabin without disturbing Mela. Outside the flitter the air was cool, but so dry there was no dew. The light was still an empty grey, and the dawn was complex, cast by multiple suns that swarmed restlessly over the horizon.

Luru Parz was standing in the shadow of the flitter’s wing, a silent pillar watching him.

`I couldn’t sleep,’ he said.

She shrugged. `You’re young. You’ll survive … Look.’

Peering into the half-light, Symat saw movement. The dark shapes were animals, a herd shifting slowly across the plain beyond the city. One animal, younger, broke away from the rest, and he saw its silhouette more clearly. He counted two, four, six legs.

Luru said, `Interesting, isn’t it? This planet was the capital of a Galactic empire. Now most of it is abandoned and gone wild.’

`I never saw an animal with six legs.’

`I believe they are called “spindlings”. They are not native to Earth. And look at this.’ She walked a few paces away from the flitter to a patch of grass.

Symat bent down and ruffled the grass with his fingers. It was dry as a bone, but it was alive, adapted to the aridity. And as the light lifted a little more he saw that among the green blades was some kind of fibrous growth, deep black.

`The green grass is probably native: there are lots of ways to exploit sunlight for energy, but using green chlorophyll is quite rare. Something to do with the spectrum of our sun, no doubt, before its modification by the photino birds. But that black mat is not a native, any more than a spindling. And - there!’ Luru pointed, almost eagerly. `See that?’

Symat saw a small shape moving through the miniature jungle of the grass. It had a silvered carapace, and he thought it might be a beetle. But then light speckled between its jaws.

`Laser light?’

`It’s descended from tiny machines designed to crop the grass. Now it follows its own evolutionary agenda. If you turn them out into the wild, even machines evolve, Symat.’

Symat thought of the bit of wild technology he had seen for himself on Mars: abandoned Virtual children, turned cannibal. And he remembered the slow liquid-helium native fauna of Port Sol, scattered by mankind to other cold worlds across the Galaxy.

Luru said, `Wherever they are deposited, living things, transported between the stars, even machines, find ways to combine, to form rich new ecologies. After a million years of spaceflight, every human world is like this. And even if mind disappeared from the Earth tomorrow, as long as the planet survives, you would be able to look at this interstellar mixing-up and say, yes, once people from this place reached the stars.’

`But this isn’t the only trace of the past.’ It was Mela; small, composed, she walked out from the shadow of the flitter. The Curator followed her.

`Oh, good,’ Luru said dryly. `Everybody’s up.’

Symat said, `What do you mean, Mela?’

`The collapsed magnetic field. The thin air, the drained oceans.’ She jumped up and drifted back down to the ground, slow as a snowflake. Symat knew it was a Virtual illusion, but she made her point effectively: even Earth’s gravity had been reduced.

Luru sighed. `Earth got used up.’

Earth, home of mankind, had been the capital of an empire which had won a Galaxy, and beyond. And for all that time Earth itself had supported a surprisingly heavy burden of the resource load.

`Earth was only rarely attacked, and never fell into enemy hands, after the lifting of the Qax Occupation,’ Luru said. `But its air, its precious water were scattered in ships across the Galaxy. Its metals were sucked from its deep interior. Its inner heat was tapped for energy.’

That was why the magnetic field had collapsed: as the planet’s heat had been drained its liquid core crystallised, and Earth’s magnetism failed. The internal cooling had also weakened the great mantle currents. So there were no more volcanoes or earthquakes, and the mountains currently eroding away were the last the old world would ever see.

Luru whispered, `In the final madness of their wars the engineers tapped into the planet’s ultimate energy store, its gravity well. They sucked out mass-energy - they reduced the effective mass of the planet. That is why you feel so light on your feet, Symat; that is why we are able to put up buildings so delicate they would seem more suited to a dwarf world like Mars. Earth is the little world that fought a Galactic war! But in the end it could give us no more.’

`Which is why,’ the Curator prompted, `you believe we must save it now.’

`Yes. And I haven’t spent half a million years striving to save the Earth from the swelling sun to see it put to the Xeelee flame now. I have a plan,’ Luru said. `Come. The dawn is rising. Walk with me into the light, and we’ll talk.’

It all depended on the Guardians, and their Snowflake cosmic-linkage technology. Luru said, `With such a technology you can do almost anything you can conceive of. Why, you can bend spacetime itself …’

And that was what Luru intended to do.

If you descended into a gravity well, you found your clocks turning more slowly than those of your colleagues on an orbiting ship, far above. All this was commonplace. Even in a gravity well as shallow as Earth’s, time passed more slowly for Symat than for an observer up there in free space. In a black hole, the deepest gravity well possible, the time-stretching effect ultimately became dominant, until at the event horizon itself time would cease to flow for you altogether.

The Curator shook his head. `Ascendent, I’m no physicist. Are you planning to turn the Earth into a black hole?’

`No. But I want to reshape its spacetime.’

Luru planned to make the Earth a pit of slow time. Just as if looking into a black hole, from the outside time on its surface would seem stretched out. Conversely if you stood on its surface, you would see blueshifted stars wheel across the sky, flaring and dying. It was possible to do all this, she claimed, by manipulating spacetime subtly; you didn’t need the immense and concentrated mass of a black hole to do it.

Mela was looking oddly absent; Symat imagined massed intelligences looking through her eyes and listening through her ears, and crowding her mind with their speculations. She said, ‘It would have to be quite a gradient. There would be a perceptible difference in the passage of time over the height of a human - a difference between your head and your toes!’

Symat scratched his head. `That would be a strange place to live.’

`People adapt. And with their lives stretched out to megayears, ‘ Luru said, `the inhabitants of Earth would be safe from the depredations of the Xeelee, or anybody else. They wouldn’t even need energy from outside, for Earth’s inner heat, reduced to a trickle, would fuel their slow-moving biosphere. Of course there are a few details to work out. This must be a long-term solution. The saved Earth - or “Old Earth” as I think of it - will need a stocked ecology, a self-renewing biosphere, some equivalent of tectonic processing. It will need a day and a night. I haven’t worked out how yet.’

The Curator laughed. `A typical Ascendent solution - to save the world with a gift of time!’

`But,’ Symat asked anxiously, `will it work?’

`Oh, yes,’ Luru said calmly. `The Guardians can do this. I’ve been able to consult them about it. They can turn their weapons on the Earth itself, and use the resources of a universe to reshape it as they please.’

The Curator shook his head. `If this Snowflake weapon is capable of such a remarkable feat, why not turn it on the Xeelee? We could scatter their fleets of nightfighters like swatting flies.’

`We? ‘ Luru mocked him. `For a shell of a programme with no personality, you have stored up a lot of aggression, Curator.’

He scowled at her taunting, and Symat could see centuries of bitterness in his expression. `Why not just answer the question?’

`We are done with fighting. After all this time, perhaps we humans have learned a little wisdom - and humility.’ She squinted up at the sky. `We humans took on the Xeelee. Remarkable when you think about it: savannah apes against a supergalactic power. We did them some damage, we drove them out of the Galaxy. But the Xeelee are far more than we ever were; we could never defeat them. And we barely noticed the true enemy, a foe of both ourselves and the Xeelee and everything made of baryonic matter, matter like ourselves-‘

`Dark matter,’ said Mela. `The photino birds in the sun.’

`In every sun - yes, child. You mayflies encountered them in the deep past, even found them in the core of Earth’s sun, and you forgot about them. You found them again later, out in the halo of the Galaxy, where dark matter dominates - the Xeelee were already fighting them there, long before our war for the Galaxy - and again, in a generation or two, you forgot what you saw. You are so infuriatingly transient!

`Well, we can’t fight the photino birds. We never could. Perhaps even the Xeelee can’t, but they are trying. There is evidence that the Xeelee are engaged in supergalactic projects, stupendous in scale - some long-forgotten explorers told tantalising tales.

`But it doesn’t matter. We humans are trapped, here in Sol system itself, between two immense forces, the destruction of the sun, and the extinguishing of the stars. Yes, Curator, we could wield our last sword and cut off a few more limbs. But we can’t win. So I think it’s better we simply vacate the stage, don’t you?

`I believe my solution is the right one. The Guardians can do this, if they have the will - and if they are ordered to. But I can’t give that order.’

Symat whispered, `Which is where I come in, is it?’

`Listen, child. The sole purpose of the Guardians is to serve humanity. But what is humanity? Since the Guardians were first installed we humans have bifurcated, innovated, rebuilt and re-engineered ourselves. Even the stock who remained on Earth and Mars, like your own family, has adapted in its own quiet way. Each of these subtypes is “human”, in that they can all trace their ancestry back to the common root. But none of them is identical to the root stock. And a biologist’s definition of humanity isn’t necessarily good enough for a weapons system.’

`Ah.’ The Curator nodded. `The Guardians are so old they no longer recognise the much-evolved descendants of their makers as human at all. Not even you, old one! What an irony.’ He shook his head and laughed.

Luru ignored him. She said to Symat, `I have found a solution for Earth - and I need the Guardians’ help to implement it. But they won’t listen to me. I needed a true human, Symat, at least “true” in the discriminating eyes of the Guardians. And, as I was unable to find one, I had to breed one …’

Genetic engineering had been considered. Even if nobody like the ur-stock of humanity still existed, there were records of their biomolecules. But the Guardians would easily have been able to spot any such engineering; they would have rejected the wretched result as a fake.

So Luru had had to resort to more natural methods. She had surveyed the human population of Sol system. She had identified stretches of raw DNA in fragments, scattered over the worlds. And she had begun a programme of patient cross-breeding, seeking to gather together the strains she needed.

It took a thousand years. But a millennium was a moment for an undying.

`And it all culminated in me,’ Symat said.

`I told you you’re different, Symat!’ Mela said. `No wonder you don’t look like your parents. And no wonder the Conclave was watching you.’

`You probably don’t look much like an ur-human either,’ Luru said dryly, `but I think you’ll fool the Guardians. And that’s all that counts.’

The Curator said, `And did these generations of toiling breeders know how you were using them, Ascendent?’

`It was safer for the project that they didn’t. A little social engineering sufficed.’

`And this is your master plan? After a galactic war and a million years of history, the future of man comes down to the decision of a fourteen-year-old child? … Lethe, Ascendent, what gives you the right to make a choice that will fix the whole future of mankind - even through this boy?’

`Only I have the vision for such a solution,’ she murmured. `Only I have the longevity to see it through. That’s what gives me the right.’

Symat said, `What would I have to do?’

`The Guardians are watching you, Symat, through the Conclave, through all our Virtual eyes. All you have to do is formulate your decision, and it will be made so. You won’t need to throw a switch.’

`It will happen straight away?’

`Why wait?’

Mela’s eyes narrowed. `And what will become of Symat?’

Luru frowned. `For a brief moment he will be the epicentre of cosmic forces. Humans are frail creatures.’

`I wouldn’t live through it,’ Symat said slowly. `I am going to die.’ But somehow even that didn’t perturb his eerie calm.

`Symat, you don’t have to do this,’ Mela said.

Luru reached out as if to touch him, but she could not, of course, `Every true saviour must lay down his life,’ she said.

`Just like your own Symat,’ Mela said. `He died for his beliefs, you said.’

`Yes,’ the Curator snapped. `And now you’ve cooked up another Symat to go the same way. What’s going on in that head of yours, Ascendent? Is this really about saving Earth, or just working out your own million-year-old guilt? Is this all about you?’

`You disgust me, Curator, you and your inane grinning,’ Luru said coldly. `You disguise your fear of me within your hollowness. But I know you.’

The Curator was obviously shocked, and again Symat saw fierce resentment burn. But he persisted. `And what will you do if he refuses? After all your planning and preparations, to be thwarted now by the whim of a boy-‘

`I will start again,’ she said smoothly. `An Ascendent always has time. You should know that, Curator.’

`Enough,’ Symat said.

They all fell silent.

He still felt calm, calmer than any of these Virtuals, it seemed. `You’re saying this is the only choice,’ he said to Luru. `The only way forward for humanity. It’s this or the booths.’

`This or the booths,’ she said.

He looked at a sky full of dying stars. He reminded himself he was a boy, just a boy with a judgement so poor he had almost got himself drowned in a canal. Who was he to make such a decision? But mankind couldn’t stay here, in this imploding system. And he could never have walked into a booth himself. Perhaps others felt that way. So there was only one choice. Yes, he was a child, but he knew that no matter how long he lived the parameters of his life wouldn’t change - and nor would his choice.

He said as clearly as he could, `I have made my decision.’

And even as he spoke he thought he felt a stirring, emanating from deep under the clouds of Saturn, as if a great storm were brewing there.

Luru’s black eyes shone. `You’ve made a good choice. You’ve given humanity a chance.’

The Curator muttered, `You have courage, boy. I just hope you’ve wisdom too.’

A wind rose, whipping up red dust that clouded the sky.

The Curator cried, `Look!’

There was a new light in the sky. The clouds of Saturn were churning, and a harsh, pitiless light broke out. It was like a monstrous egg cracking, Symat thought.

Luru Parz laughed.

Mela cried, `So quickly?’

Luru smiled. `The Guardians have waited a million years to act. They are ready.’

But Symat wondered if he was ready. He knew he was too young to have come to terms with the idea of personal death. Now, suddenly, he was going to have to face it.

Mela ran to Symat and tried to grab him. The wind noise was too loud for him to hear the inevitable protocol chimes. Her eyes were wide, her face torn, as she yelled at him.

`What did you say?’

She screamed louder. `It may not have to be this way …’

The egg cracked wider. Glass smashed somewhere in the city behind them, and every grain of dust on Earth took to the air. A tremendous light flooded the sky, dazzling him. And then-

VI

`Can you hear me? Symat, can you hear?’ It was Mela’s voice, but she was far away.

It was like waking up. But he had no sense of his body, of a bed, of blankets and sheets. He was surrounded by light.

He was light, he thought, but the idea didn’t disturb him. He was light, coming into focus.

And suddenly he could see. Mela’s face hovered before him, creased with concern. Beside her were other children. He recognised Chem, Tod.

He was standing. For a moment he was disconcerted, as if finding his balance, and he staggered slightly.

He stood on dusty ground, beside the crystal waters of a canal. A malevolent sliver of red sun poked above the horizon, but the air was still and pleasantly cool.

`So I lived through it.’

`Sort of,’ said Chem.

`Earth has gone,’ Mela said. `Sent off into the future. But Mars is still here.’

`My parents-‘

`They are coming.’ She looked more serious. `It will be difficult for them. For you.’

He looked at his hand. `I’m a Virtual.’

`Yes. You’re a Virtual.’

`My mother won’t be able to touch me. My parents will feel as if they have lost me.’

`And you have lost them. But you have found us.’ Impulsively she reached for his hands - and held them. Her palms were warm and soft.

He smiled. `I told you I’d come back,’ he said to Chem.

Chem grinned.

`You took your time,’ Tod said.

`Listen,’ Mela said. `Can you hear them?’

Symat glanced around. `Hear what?’

`Not outside. Inside.’ She tapped her chest.

When he listened inwardly, he could hear a distant murmuring, voices merging like a sea. It was the Conclave, the community of minds that spanned Sol system and now embraced him, a community of which he would be a part for ever. `Yes,’ he said. `Yes, I hear them.’

`So what do you want to do now?’

`I don’t know-‘ A child’s shoe hit him in the chest.

Tod had thrown it. `You can save the world, but you can’t catch me!’

`Oh, yes? …’

The four of them ran, and their laughter echoed from the banks of the drying Martian canal.

005

So Earth died but did not die. So Symat died, but did not die.

I did not die, of course.

How could I die? I had completed this project, but I have completed projects before, and history just keeps on piling up, whatever I do. So here I am, in the dark, alone.

Waiting for what comes next.

I remember so much, yet so little. I have seen mankind rise and fall - quite a story! But what stays with me are the faces, the endless torrent of faces, from Symat the ragamuffin whom I loved, to Symat the idealistic messiah-boy whom I bred to die. Each face blossoms like a flower and fades to dust, leaving me alone once more. Each face is a betrayal. Yet they are all I have.

Sometimes it feels as if it has all been a dream, from the instant I put Gemo Cana’s pill into my mouth. Perhaps in a moment I will wake to find myself under the shining domes of Conurbation 5204. And then, with my cadre siblings, I will run, laughing, in Sol’s yellow light.

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