It takes him a while to get used to the cramped little bed, but the mere argument of warmth makes him prefer it to the couch nonetheless.

So Shion bears with the movement, the little space, the constant shoves and kicks, and occasional acquaintances with the floor.

And as the time stretches on, he realises he actually likes it. Perhaps not the bruises, or the sudden pain when colliding with the floor, but the proximity and the feeling of another living being close to him.

Some nights, when he's sure Nezumi's asleep, he shifts so that he's able to lay his head onto Nezumi's chest and listen to the steady beating of his heart, feel the constant heaving and sinking of Nezumi's ribcage as he breathes.

Nezumi told him that the only thing Shion needed to know about him was that he was alive and that he intended to stay that way.
It still sounds to Shion like a cheap excuse, as if Nezumi doesn't trust him. Or perhaps he only doesn't trust himself, Shion can't actually tell.
Safu would probably have Nezumi figured out in a second, would be able to tell what he'd been going through and what he is thinking.
Yeah, Safu is that kind of person, reading your neuronal reactions and knowing what moves you, a specialist at applied knowledge in the area of psychology.
But Shion isn't and so he can't tell, can't figure what Nezumi is thinking unless he is told.

And so he takes up the chances to listen to Nezumi's heartbeat as if it would be more willing to tell something about his owner than its colleague, Nezumi's vocal chords.
It doesn't, obviously, but the sound itself is enough to calm Shion down, no matter how troubled he might be, how much his body aches from a day of physical labour, how much he misses Safu and his mother; Nezumi's heartbeat and breathing always make everything vanish from his mind, until there's only them, only Shion and Nezumi, and the rest of the world doesn't matter anymore.

Nezumi's alive.

Yeah, actually it's all he needs to know.

Nezumi's alive and I am alive.

It's all it's ever been about.

That he and Nezumi are alive.

And in one of those moments he whispers the words, directly to Nezumi's heart, as if they would reach it easier if spoken as close as possible; he tells his heart how much it means to him, how much that beating means.

He now repeats the words he already told Nezumi, since he knows he would brush them away once again if he was awake, but Shion wants the words to stay in the air, to etch themselves into Nezumi's heart, so that Nezumi won't be able to forget them ever again.

What Shion doesn't know is that almost every time after he falls asleep on Nezumi's chest, lulled by the beating, grey eyes open to the darkness, which hardly is any hindrance for them as they face down, down to the mess of white hair, draped contently on his chest.
What Shion doesn't know is that Nezumi's not only good at acting on stage, but at acting in every situation of his life.

And he probably doesn't know how helpful it can be to be able to fake sleep, since all people are less careful around persons they believe to be asleep.
But whenever Nezumi feels Shion shift, he knows what the white haired boy's going to do, and every time he contemplates if he should simply show or tell Shion that he's awake but he never finds the courage to do so, actually enjoying the weight and the warmth of another body so close to him.
He's used to the little bed and being by himself and even though he doesn't like to admit it, the sound of another breathing combined with aforementioned weight makes him feel safe, comfortable even.

But whenever he knows that Shion listens to his heart, he fears it might give him away—the traitorous little thing—fears it might start thudding louder, fears it would make a throbbing sound instead of sole beating, since that's the way it feels when Nezumi knows Shion's crossing boundaries he should leave uncrossed, when he feels Shion becoming inevitably attached.

So after Shion's whisper he opens his eyes and stares at the white mess of hair, rakes his fingers through the soft streaks, relishing the satin feeling of it.
He can perfectly tell when Shion's asleep, since Shion is no actor.

And knowing that Shion is asleep causes him to let his guard down as well, to do the same thing he makes fun of others for.
And when he answers his voice isn't more than a mere whisper as well, as if the words are to precious, as if they would break if they're spoken to loudly.
Or as if he might break, if anyone would actually hear them beside his books, and the cold, damp air.

He whispers how inexplicably, how strangely and impossibly he feels the same, how it is no longer only his own heartbeat that's on his mind but another one, one that snuggles that close to his sometimes you could think they were one, but they weren't and it scares Nezumi that suddenly he has a second heartbeat to watch over.
With those thoughts on his mind, his arms find their way around Shion's shoulders more often than he would like to admit. And when he holds Shion, when he draws him a little closer, carefully, as not to startle him, when he takes deep breaths to inhale Shion's scent, sleep comes almost instantly.

And the thing that both don't notice is the way they both sleep with a smile on their faces whenever they're entangled like that, their heartbeats mingling until they're one steady noise that keeps the cold from their dreams.