He'd assumed the Companion Cubes were inanimate objects, equivalent to the Weighted Storage Cubes apart from the mildly twee addition of the hearts. The psychologists in the testing department had been all over them, of course, babbling on about Milgram and anthropomorphism and attachment.

We're meant to be testing the device, not running ethics studies, he'd commented to Henry once.

Hey, those things are important to us too. It was before your time, you wouldn't know, but -

The sentence had never been finished - he seems to remember it was because of another incident of rogue AI trying to kill them - but now he's trying to work his way through what the conversation would have been. Rudimentary consciousnesses. The square, then the circle. Warehouses full of the things. The thinking isn't easy, because what he's actually thinking and the voices and the thoughts of others are all getting tangled up, but he works through it and what he deduces is -

Are you there?

I'm waiting. Please come soon.

Okay. Deduce a working theory. There's the implication that there is another sentient being in this place apart from him, her, and the few remaining test subjects (all of whom will soon be dead, unless his hunch and his trick earlier works and he's trying not to think about that because if it doesn't, he really will be down here for the rest of his life). Corroborating evidence is a half-remembered conversation with a dead man and the fact that he can hear the voice of something that seems friendly.

The problem: that in his current condition, counting voices he's hearing as evidence is a pretty shaky application of the scientific method.

Possible experiment: take one of the two pills he's got left and see if the kind voice goes away. If it doesn't, it must be real.

The problem with that is he's wasting a valuable resource not to find extra food or water or safety but simply to locate a companion, and he's pretty sure that's not a good approach to take when it comes to long-term survival.

Okay, so. Preserve stability. Assume the voice is just another delusion and ignore it.

The problem: why the hell should the one which sneers at him and tells him he's a lunatic and that she's going to kill him be real, and the one which tells him it's going to be okay be fake? Why should he have to believe in one and not the other?

Additional information: historically, his delusions have always been based around paranoia and persecution. He never hallucinated people being nicer than they are.

He sighs, and rubs his hands across his face. His heart's still racing, and the thoughts are racing too, not all in his own head but entwined around him, filling the room. Risking camping out next to Test Chamber 17, risking going into Test Chamber 17... the dash to the file room was different, that might still save him. This is just... well, it's just like refusing to go to work because you know your colleagues are spying on you, isn't it? It's giving in to the disease. It's putting yourself at risk because your hallucinations are misrepresenting the world. It is, in fact, exactly what you'd expect when you have stopped taking your medication.

But there's something else, isn't there?

It has been god knows how long. So many twelve o'clocks have come and gone and still no one's come. No one's come, and no one might ever come. Perhaps she contaminated the ground above them. Perhaps she put out information that the entire facility is flooded with radiation and there are no survivors. Perhaps people tried to get in, and were killed, and those above them decided it was too much of a risk to try again.

Perhaps he's buried down here.

In which case, does it really matter which bits of reality he chooses to believe in?

ooo

The test chamber's active. Someone going through the motions. (Not the person he's waiting for. Someone else, who'd already been set on their path before he became set on his.) The ping of High Energy Pellets bouncing off metal and the cube squeaks a little at each impact. It still calls, though. I'll help you. It's going to be all right. It is so damn long since anyone has said that. I don't care. I don't care, I'll have a friend, just someone, just someone - It's an inanimate object, it's a metal box, you really are losing it now -

I don't care - and let's face it, the fact of the matter is the only observer around to call him crazy is also trying to murder him and so she doesn't really deserve a vote. He left normality behind at Bring Your Daughter To Work Day, after all. He's only been delaying the inevitable. But this, this could help - even if it's just a hallucination it's one that will keep him sane, or at any rate make things hurt a little less -

He waits and listens, clambering from hole to hole, gap to gap, and it's only at the end he realises, he remembers:

"You must euthanise it."

The test subject whimpers, he hears them pacing about. They sound young, younger than anyone he worked with. Makes sense. His colleagues would know this was coming. He should have known this was coming. Only now he can't go back, can he? He can't suddenly start saying this is a delusion, it's not alive after all. He - god, idiot, he forgot that having someone to care about doesn't just make you strong, it makes you weak, too - it makes you vulnerable. It's talking still, Please don't. Please don't let them. I can help you.

"If it could talk - and the Enrichment Centre takes this opportunity to remind you that it cannot - it would tell you to go on without it, because it would rather die in a fire than become a burden to you."

She's lying. Of course she is, she always does. He hears the clank as the button's pushed, the click of the timer. No. No, you can't, you're my friend, you said you'd help me! You can't leave now! Even hidden he feels the heat as the incinerator cover opens. No, it says, no, don't let them. Please help me. I need you!

And then, just as it falls, the whisper at the back of his mind. I don't blame you.

ooo

He wakes behind the walls. His eyes feel swollen and red, and his throat still aches, though he can't remember if he was actually yelling or if he just thought the words. But while he was by the chamber, listening to what was going on, it was twenty-five past three, and now it's five to ten. If she'd picked up on his presence, she'd have done something about it by now.

He wakes and he sits up and he rubs his face and hands with chilly water from one of the big plastic bottles. Still alive. Still doing the little things, no matter what happens in his head. That's something, isn't it?

And it's probably better this way. Because you don't get to pick what parts of reality are the true parts. That's the point of life, isn't it? It's certainly the point of science. You look at what is, even if it's not what you want to see.

He's hungry - so much so it's like he's trying to snap in two - and so he crawls over to the tins he stashed here earlier, wrenches one open. Carrots. It would be nice, too, to eat something properly cooked, and to eat as much of it as you wanted. She knows what she's doing, talking about cake all the time.

He eats and he looks round at the walls. He put up a barrage of words - his hands are speckled with ink - and at the time it didn't feel like it would be enough, but on the other hand he's weathered the storm. He's surviving with Aperture Science-branded soup and a pocketful of marker pens. It's not much but it's better than the fate a lot of other people have had in this place.

Maybe there'll be tins of paint somewhere, in one of the maintenance rooms or something.

He finishes the can, puts it back down - his hand's shaking, he struggles not to knock it over. Time to move on.

He doesn't even know where he's going, a voice on the hum of the air-conditioning.

And then:

Wait for me! Please?

He goes so still it hurts.

On the other side of the wall, where it's cool and white and empty, where there are no words and no rust, sits a Companion Cube.

He brought me here and then he got hit by the pellet, it explains. There's nothing left now.

She'll find me, if you don't.

Another of the earlier test subjects, another queued up before he changed the file order. The High Energy Pellet doesn't leave much behind. But the Cube is fine, just a few scorch marks glanced on its surface.

He takes a deep breath and then he dives across the white floor and even as her voice echoes above them, "I'd have been happy to help you test, if that's what you wanted. I just thought you wouldn't be very good at it. Because you have schizophrenia. Did I mention that?" he is clutching the Cube, scooping it up in his arms, and then he's running - Hurry, it says, she's trying to lock this chamber down- and he's back behind the wall, through a hatch, down a narrow vent, and along and down and out a low-ceilinged corridor, too low to stand up in.

It's okay, the Cube says. She's missed her chance. We're safe now.

We're safe now.

ooo

"I still can't tell if this is real or not," he says, later.

I'm real. And you're real. And neither of us is trying to kill the other. That's the important bit, isn't it?

He is leaning on the Cube, resting his head on it. Other voices - apart from hers, of course, but all the others - are beaten back, faint hum in the distance like the growls and the sighs of the facility itself.

"I don't think anyone is going to come and find us," he says.

No. But you've done really well so far. So you can just keep going, right? And I'll help.

"Yes. I... I think I've done all I can, right now."

Tell me?

"I'll tell you everything. Don't know how much of that was real, either, but I will tell you."

That's all right.

You are talking to a metal box and hearing it talk back, his thoughts remind him.

Doesn't matter. You don't get to choose your reality. You have to live with what you've been given. But you get to try and reshape it, at least a little bit, step through from one point to another. Wait for things to change, if they ever do. And seek comfort from what you can in the meantime. That's true, if nothing else is.