"Sherlock." The detective stops, looks at the tired man standing in the hall.

"Mm? Oh, you're annoyed."

"Stop. Pacing. It's impossible to sleep."

John draws a hand across his face and blinks, hard. Sherlock stands quietly, hands clasped behind his back. To the unstudied observer, he looks calm and unaffected as ever; to John, he is absolutely distressed.

John leans against the doorframe and crosses his striped-jumper-clad arms across his chest. He raises his eyebrows, wets his lips, and waits.

There's a tense moment as they stare at each other. Sherlock says nothing. John yawns.

"Sherlock. It's three in the morning. What could you possibly be thinking about that requires you to pace—no, no—stomp around outside my door? Mm? Did you even think that maybe I would be asleep?"

"Mm? Oh, no, not really." Sherlock sounds distracted, and it worries John to no end, reminds him of pill bottles and a shot through two windows, of near-certain death and cabbies and a stupid, stupid desire to find out why.

"All right. I know something's up." John continues staring, eyes expectant and heavy with sleep (or lack thereof, he grumbles to himself). Sherlock meets his eyes, crosses his arms too.

"Oh, I see," John sighs. "You want me to deduce something. Oh, aren't you clever. Look, it's 3:00 AM. I'm going back to bed and I'll play your stupid game in the morning. You know, once I've actually slept for more than half an hour."

Sherlock looks slightly crestfallen, but again, it's barely noticeable—just a dip in the eyebrows, a tightening of the mouth. John thinks perhaps his mind (his poor, sleep-deprived mind) is playing tricks on him. He blinks again, shakes his head.

"John," Sherlock begins. John sighs.

"Look, John, I need you to figure something out for me. Please."

John reels slightly from the shock of Sherlock asking for something politely.

"Sorry, did you just say please?"

"What? Yes, yes, never mind. Anyway, John…"

"Oh, god. No, Sherlock, I'm going back to sleep. It can't be that important; we just finished that bloody case about the ballet studio." He starts back into his room, then thinks better of it and turns around again. "And it wouldn't kill you to get some sleep either. Whatever it is, we can talk about it later. Goodnight."

As he shuts his door behind him, John hears a noise he's never heard from Sherlock before, like a panicked intake of breath but more vocal, gasping and releasing air like a man who has very little time left to breathe.

"Dammit, John!" Sherlock shouts, a little too loudly for the hour. "God, will you just listen to me? No, it cannot wait; why else would I possibly be here in front of your room? I know what time it is! It wasn't an accident; I need to talk to you!"

Ah. This changes things. John opens his door again and is faced with an unmistakably livid Sherlock.

"All right. I'm listening."

John levels him with a patient gaze. Sherlock's mouth works a bit, and he swallows. Honestly. John can't remember a time ever when Sherlock was less than perfectly cool and confident. Ever.

Finally, Sherlock looks up (well, sort of) to meet John's eyes.

"John."

"…Yes, Sherlock…"

"I don't normally sleep. I don't really like to eat, either. And… honestly, I'm usually fine. I don't get tired, I'm never hungry. I don't really care if I leave experiments and poisonous things around the house. I… just… I just…" He trails off.

"…Where on earth are you going with this?"

"Well, see, that was before you moved in here."

John stares at Sherlock. Sherlock stares at John. Apparently Sherlock is done talking. John waits a moment, just to be sure, but Sherlock is looking at him like he expects John to have made some great revelation by now.

"…and?"

"Don't you see, John? I'm different now! I eat sometimes, even when I'm on a case! I slept last night, for four hours, mind you, and today, I washed my tea mug."

"What a miracle," John mutters. Sherlock's eyes never leave his face, though they're flickering back and forth, as though he's concentrating very, very hard.

"No, John, you don't understand. It's like I always say, you know, you see but you do not observe. It's not a miracle. I've done it all before, honest. It's just… It's… well, John, I did it for… because of…"

Sherlock's gaze drops to the floor, and John gets it now.

"…You're different now… because of me?"

Sherlock brings his eyes back up to John's face. He says nothing.

"You're saying… that… you eat, now, and sleep and clean and all that… because of me?"

"…Yes."

And the full force of everything John did not understand before comes crashing down onto his head. Everything—every smile and ridiculous dash through London and every single time Sherlock has ever said 'you coming?' with that hint of amusement and now, he knows, affection on his face. Every moment. All of it.

And it makes sense, now.

It's right.

"Sherlock, I—" and John Watson can't speak anymore. He rushes forward, grabs Sherlock, and pulls him into a hug, too-close-for-brothers and full of emotion. Sherlock buries his face in John's shoulder, breathes in the scent of tea and freshly-washed wool. When they separate, minutes later, John grabs Sherlock's hand.

"Come on then, let's get some sleep."