Well, it seemed now, she’d been wrong. These people — of her own era, roughly, preserved by relativistic time dilation in their strange ship, the Great Northern — had returned to the Solar System.

And they were — she’d come to believe — people who didn’t approve of her.

They hadn’t said as much, explicitly. But she suspected an inner coldness was there, buried in the long communications they exchanged with her.

They thought she’d lost her objectivity — forgotten the reason she was placed in here in the first place. They thought she’d become an ineffectual observer, seduced by the rhythmic beauty of the photino birds.

Lieserl was some form of traitor, perhaps.

For the truth was — in the eyes of the men and women of the Northern — the photino birds were deadly. The birds were anti-human. They were killing the Sun.

They couldn’t understand how Lieserl could not be aware of this stark enmity.

She closed her eyes and hugged her knees; the hydrogen shell, fusing at ten million degrees, felt like warm summer Sunlight on her Virtual face. She’d watched the photino birds do their slow, patient work, year after year, leaching away the Sun’s fusion energy in slow, deadly, dribbles. She’d come to understand that the birds were killing the Sun — and yet she’d never thought really to wonder what was happening outside the Sun, in other stars. Had she vaguely assumed that the photino birds were somehow native to the Sun, like a localized infection? — But that couldn’t be, of course, for she’d seen birds fly away from here, and come skimming down through the envelope to join the core-orbiting flock. So there must be birds beyond the Sun — significant flocks of them.

She realized now, with chilling clarity, that her unquestioned assumption that the birds were contained to just one star, coupled with her intrigued fascination with the birds themselves, had led her to justify the birds’ actions, in her own heart. It hadn’t even mattered to her that the result of the birds’ activity would be the death of Sol — perhaps, even, the extinction of man.

She quailed from this unwelcome insight into her own soul. She had once been human, after all; was she really so clinical, so alien?

The murder of Sol would have been bad enough. But in fact — the crew of the Northern had told her, in brutal and explicit detail — all across the sky, the stars were dying: ballooning into diseased giants, crumbling into dwarfs. The Universe was littered with planetary nebulae, supernovae ejecta and the other debris of dying stars, all rich with complex — and useless — heavy elements.

The photino birds were killing the stars: and not just the Sun, man’s star, but all of the stars, out as far as the Northern’s sensors could pick up.

Already, there was nowhere in the Universe for humans to run to.

And she, Lieserl — the Northern crew seemed to believe — should be doing more than leaking out wry little messages via her maser convection cells. She should be screaming warnings.

Through her complex feelings, a mixture of self-doubt and loneliness, anger erupted. After all, what right did the Northern crew have to criticize her even implicitly? She’d had no choice about this assignment — this immortal exile of hers in the heart of the Sun. She’d been allowed no life. And it wasn’t her who had shut down the telemetry link through the wormhole, during the Assimilation.

Why, after millions of years of abandonment, should she offer any loyalty to mankind?

And yet, she thought, the arrival of the Northern, and the fresh perspective of its crew, had made her take a colder, harder look at the birds — and at herself — than she had for a long time.

She pictured the shadow universe of dark matter: a universe which permeated, barely touching, the visible worlds men had once inhabited… And yet that image was misleading, she thought, for the dark matter was no shadow: it comprised most of the Universe’s total mass. The glowing, baryonic matter was a mere glittering froth on the surface of that dark ocean.

The photino birds — and their unknowable dark matter cousins, perhaps as different from the birds as were the Qax from humanity — slid through the black waters like fish, blind and hidden.

But the small, shining fraction of baryonic matter seemed vital to the dark matter creatures. It was a catalyst for the chains of events which sustained their species.

For a start, dark matter could not form stars. And the birds seemed to need the gravity wells of baryonic stars.

When a clump of baryonic gas collapsed under gravity, electromagnetic radiation carried away much of the heat produced — it was as if the radiation cooled the gas cloud. The residual heat left in the cloud eventually balanced the gravitational attraction, and equilibrium was found: a star formed.

But dark matter could not produce electromagnetic radiation. And without the cooling effect of the radiation, a dark matter cloud, collapsing under gravity, trapped much more of its heat of contraction. As a result, much larger clouds — larger than galaxies — were the equilibrium form for dark matter.

So the early Universe had been populated by immense, cold, bland clouds of dark matter: it had been a cosmos almost without structure.

Then the baryonic matter had gathered, and the stars began to implode — to shine. Lieserl imagined the first stars sparking to life across the cosmos, tiny pinprick gravity wells in the smooth oceans of dark matter.

The photino birds lived off a trickle of proton-photino interactions, which fed them with a slow, steady drip of energy. And to get a sufficient flow of energy the birds needed dense matter — densities which could not have formed without baryonic structures.

And the birds’ dependence on baryonic matter extended further. She knew that the birds needed templates of baryonic material even to reproduce.

So baryonic-matter stars had given the photino birds their very being, and now fed them and enabled them to reproduce.

Lieserl brooded. A fine hypothesis. But why, then, should the birds be so eager to kill off their mother-stars?

Once more the chatter of the humans from the Northern passed through her sensorium, barely registering. They were asking her more questions — requesting more detailed forecasts of the likely future evolution of the suffering Sun.

She sailed moodily around the core, thinking about stars and the photino birds.

And her mind made connections it had failed to complete before in millions of years.

At last, she saw it: the full, bleak picture.

And, suddenly, it seemed urgent — terribly urgent — to answer the humans’ questions about the future.

She hurried to the base of her convection cells.

The shower’s needle-sharp jets of water sprayed over Louise’s skin. She floated there at the center of the shower cubicle, listening to the shrill gurgle of the water as it was pumped out of the booth. She lifted her arms up and let the water play over her belly and chest; it was hot enough, the pressure sufficiently high, to make her battered old skin tingle, as if it were being worked over by a thousand tiny masseurs.

She hated being in zero-gee. She always had, and she hated it still; she even loathed having to have a pump to suck the water out of her shower for her. She’d insisted on having this shower installed, curtained off in one corner of the life-lounge, as her one concession to luxury — no, damn it, she thought, this is no luxury; the shower is my concession to what’s left of my humanity.

A hot shower was one of the few sensual experiences that had remained vivid, as she’d got so absurdly old. High-pressure, steaming water could still cut through the patina of age which deadened her skin.