It is a Sunday in May with the rain cracking against the thin glass of the window in the way that rain so often does in English cities. Thin, wan lines of light make strips of the floorboards glow. B has blood on his fingers from playing with a mouse and a knife. He pushes against the heavy wood of a door, expecting to find an empty room, but instead opens the door onto the centre of the universe.

He is tall and thin with dark, shaggy hair that falls over an incredibly young looking face. His hands are pressing against his mouth and he is looking at the floorboards with disinterest. According to the words dancing over his head his name is L Lawliet. L. It is at this precise moment that the world shifts.

B kinda feels like he should drop to his knees and start praying but he also kinda feels like he should run away and never come back. He mutters an apology and dashes away.

.

A isn't in his room, so he must be in the abandoned church that perches on the hill overlooking the orphanage, because he's never in the woods when it's raining. When B finds him, he is doing that strange thing where he presses his fists over his eyes and makes strange wailing noises. B lopes over and folds himself onto the floor neatly. "Hi. Why are you doing that? I saw L."

A has tucked himself into the shadows, into a corner of cold stone where the dull light streaming in from the huge windows does not dare venture. His pale skin makes him a ghost against grey brick. His shoulders are shaking and he does not seem to care about L.

"Why are you doing that?" B asks again. He is beginning to lose his patience.

"I found the cat," he says, shakily. "You know, the cat, the orange one, the one we liked, you always used to stroke it and it'd always come up to you. It liked you."

B knows exactly why A is using past tense to describe the cat, but he feels like it would be more amusing to make A explain. "Why are you using past tense?" he says, playing dumb, with furrowed eyebrows and tilted head not befitting the world's future best detective.

"I'm sorry." His voice is a whisper.

"What are you sorry for?"

"I found it in the woods - it was covered in blood, cuts all over it - it was horrible, B," he says.

He sits back, dropping the confused expression in favour of a shocked one. "It was dead?" He hopes it wasn't.

A shakes his head, but still doesn't look up. "No, it was just lying there, these huge cuts on its side, and just making these sad little noises. I went over to it, kneeled down next to it. It was screaming, it really was, it was in so much pain, so I went back into the kitchen and got a knife and stabbed it, right in the heart, so - so it wasn't going to be in pain any more."

"You killed it."

He winces. "It was already going to die."

"Yeah, but you, you killed it." B leans against the wall and stares at the sun until its image is burnt into his retina.

"It was probably a fox or something, that mangled it in the first place, probably."

B nods. A's sobbing has subsided slightly, and soon the boy relaxes enough to uncurl. He stretches out his legs and presses his white palms against the wall, tilting his head upwards. B mirrors him almost exactly.

"I saw L," B says.

"Okay," says A.

"He was wonderful and he looked young and he was standing up straight against the wall when I first came in. Then he slid down the wall a little into a slouch. He was wearing a white shirt and blue jeans. He didn't look like the person we're told about, but it was him, and he was wonderful. His fingernails - "

"I don't care about his fingernails, B."

"I do. Because I care about L. We're meant to be him. Fingernails might turn out to be important!"

A sighs. "I don't care about L." The church feels suddenly much quieter. The crashing of rain on the roof and the caws of birds remain constant, but there is a new silence hanging there.

A is the kind of student who will revise all night to get top marks. B is the kind of student who maybe takes a quick glance at his notes in the minutes before a test, but still manages to only get one question wrong. If this trend continues then A will become L. And that cannot be right because A doesn't care about L. A doesn't deserve to be L. A needs to be removed from the race before he can beat B.

B looks above A's head and wonders when the numbers changed.

.

B does not see L after that night and does not expect to. He spends his days avoiding C and D, fidgeting his way through classes on how criminals think, and plucking the feathers from birds' wings. Sometimes he spends the whole day perched on the highest branches of the trees, perfectly still, waiting for a butterfly to come close enough that he can snatch its wings away. He goes barefoot, his toes wrapped around twigs. By the time L returns, B has worn nothing but baggy jeans, underwear, and a white shirt for two and a half years. He sleeps for little enough that black semicircles are etched under his eyes. His posture is twisted from years of slouching.

He looks down on the newly-arrived children both literally and metaphorically. They are nowhere near as good as A. They are nowhere near deserving to be L. He doesn't bother getting rid of them.

It is mid-December and snow has begun to fall. From B's vantage point on the branch that taps on his window on windy nights, he can see the thin road winding up to the orphanage. Usually it is completely isolated and the only thing that travels down it is the wind and Roger on shopping trips, but today a small grey car arrives at the orphanage.

The car door opens; he can see L limping in, accompanied by Quillsh. L, limping. A person who exists to be strong showing a sign of weakness.

He thinks he might be sick. Nobody is meant to see this. Nobody deserves to see L like this. Even so, he climbs down the tree and scampers after him.

From the shadows he hears them talk - them being Quillsh and Roger, as L doesn't seem to want to say anything. They discuss the circumstances of L's injury and how it wasn't them who caused it, it was just unfortunate that the man they had sent him after was a little trigger-happy, it was pure coincidence that the case seemed a little too similar to the tests they had once set him. L just looks at the floor. B stares at him for a while through the crack in the doorframe, his heart beating frantically. He isn't that far away from L. If he wanted to, he could probably touch him.

The conversation soon turns to how L will be helped to recover. "You'll be staying in the room you used to," says Roger, "and we'll make sure you get medical care."

B knows where L's room used to be, so he doesn't really need to hear anything more. He leaves the door and heads upstairs. The room is unlocked. The layout is familiar to him - almost every room here is set out the same way, with a bed on the left, a desk below the window opposite the door, and a large dresser next to the bed. L's is no different, which is odd, as L is very different. He crawls under the bed and curls up there.

It is dark and smells of old clothes and rotting wood, like most of the orphanage, but it also smells oddly of sweets. There are a few dusty fruit gums stuck to the carpet. After an hour of lying under the bed, B takes one and chews on it.

By the time L arrives B is feeling rather sick from the sourness of the sugar. It sticks to his teeth and makes him nearly choke on the wonder he feels when L finally walks in. He collapses onto the bed just as B crawls out from underneath it.

"Hi," says B, grinning.

L's eyes are cold and tired. "Is this another test?"

He grins at him and perches on the edge of the bed. "You know I love you. I do, I really do. I love you, L. I was put in this world to find you and love you. You're my destiny, and I'm your destiny, and we're going to be loving each other for the rest of our lives." B recites it as if it's a list of facts, which it is, of course. He turns to gaze at L intently.

L draws his knees to his chest. "Go play with A."

"A's dead. He killed himself."

L is quiet for a moment. He can probably tell that B is lying – though nobody has been able to tell so far. B is an extremely good actor. Even now he is watching how L's body shakes and copying it.

"How sad," he says eventually.

"It happened years ago. You don't like us enough to keep track of us. You wouldn't care if I died, would you?"

"No. Go away."

"When I die it'll be your fault. Everything's your fault, because everything's you. You're everything and I'm part of everything so really, I'm you and you're me and everyone else is nothing and nobody else needs to exist, it just needs to be us."

L stays very, very still,. so B kisses him. Just to get him to move. It isn't a very pleasant experience.

He still does not move.

B examines L's leg for a few minutes, then presses his fingers into the wound.

"Stop that." His voice is much colder now, but still he has not moved.

He does not stop. "Who did that to you?"

"It doesn't matter now that he is dead."

There was once a man who visited here often, bringing loose sheets of paper and dull whispers and quiet, meaningless glances. His death date had been only a few days ago, but B can't remember his name. "We're all dead, I think."

"Go away." L's voice is finally starting to show some kind of emotion other than a monotone. Finally.

"I know I'm dead because in real life you wouldn't like me enough to let me get this close to you. You'd have killed me by now and therefore you've already killed me and I am dead, or I am already dead and you haven't killed me because why kill me if I am dead? And you must be dead too."

"Go away." He attempts to push B away with the palm of his hand; the push is far too weak to even dent B's balance. He wonders if L was even trying.

"I think that once you must have been human. A real person with real bones and real blood and a real soul. But now you're not that, you're not anything, you're more than anything. They made you this, didn't they? They made you into L, and L isn't a human, L is a letter. You're not human. So the human you died."

"Go away."

"It's like the ship, isn't it?" B knows exactly what he's saying. He's been rehearsing for this his whole life. Every conversation with A was just practise. "There's a ship and it's made of wood but then they start replacing the wooden parts with metal parts. When does the wooden ship become the metal ship? When does a human become L?"

L does not ask B to go away.

He sits there, eyes wide open, and he looks so young. His hands are curling up into fists and his jaw twitches occasionally. He looks like nothing.

"Is this a – they sent you up here, didn't they?" he spits. "They're doing that thing where they take me apart and rebuild me again, aren't they? They sent you here to break up my mind and now they're going to wait until I'm a mess and then they're going to build me up again!" His voice has suddenly become a scream.

B nods.

"I'm sixteen years old and I've never done a thing they didn't want me to do! Eleven years – and they've made me into some kind of robot!" Emotion seems to be hard on L. He quietens almost immediately, sealing the words away, and rearranging his body to curl around his heart. "Who am I?" he says, in the monotone again.

B looks above his head. "You're L Lawliet."

Then he scampers away, back to the safety of his room, and he never sees L again.

.

After his face is put back together, B looks almost exactly like L. He wonders often if L made sure it would turn out this way just to torment him. He wonders when he became L.

Whenever he is allowed to use a mirror, he bites his finger so hard it breaks the skin, and smears the blood over the reflection of his forehead. He writes L Lawliet every time, but never writes a death date. L will live forever.