The change comes quietly after Sherlock comes back to life.
Sherlock says later that he’d more or less expected John to hit him. Shout, at the very least. But when he’d turned around in his office and seen, of all people, Sherlock Holmes, the world tipped sideways and the only moving John did was fainting dead away.
He blinked awake again a few minutes later in his chair with Sherlock looming over him, looking stricken.
“My apologies, John,” he said. “I had no idea you would be so affected.”
“You daft bastard,” John choked out between wheezing laughs. “You daft fucking bastard.”
John had gone back to Baker Street eventually, of course, so all there was to do was move Sherlock back into the downstairs bedroom. From then, the change was natural and quiet. It was so quiet that when John proposes to Mary not long after, she just laughs sadly and turns him down with a kiss on the cheek.
“I love you,” she says, “but your life doesn’t need me in it. You’re already half of a different whole.”
Three years ago, John would have started stammering with his old insistence. “We’re not a couple.” But things had shifted, he realizes, in the park that unseasonably cold July morning, and he merely huffs out a laugh.
“My God,” he says. “I am, aren’t I?”
Sherlock knows as soon as the door bangs shut. He is up and across the room in an instant, hands on John’s shoulders, eyes narrowed and brow furrowed with concern.
“She turned you down.”
John smiles ruefully. “Yeah. Gist of it was she said she’d feel like the other woman.”
Sherlock frowns for a moment, then: “...Oh.”
John nodded. “And then I said...she wasn’t wrong.”
Sherlock’s breathing seems to still. John fools himself into thinking his heartbeat does too, just for a moment. “Wasn’t she?”
John smiles and takes Sherlock’s hands.
This seems to be enough of an answer for him, as his face and entire body relax incrementally into a smile. “I see.”
They are both smiling now. Nearly a minute passes, during which neither of them say anything at all, lost in the smiling.
“We’re not having sex,” Sherlock says.
John snorts. “Shouldn’t think so. Don’t take that the wrong way or anything, you’re just...er, not my type.”
The corners of Sherlock’s eyes crinkle. “The sentiment is mutual. But...this.” His eyes flick down to their hands and back up. “This is...acceptable.”
“Sleeping together” is both the most and least accurate term for what they do.
It is most accurate in that they share a bed and they sleep, often while in physical contact with each other. It is least accurate in that the connotations of the phrase “sleeping together” tend towards the sexual, which is entirely not the point.
It started because Sherlock doesn’t just not sleep, he often can’t. Couple that with his surprisingly ferocious need for physical affection, and they settled early on that the most sensible arrangement was to share a bed.
It works like a charm. There are many nights when John is woken at a hideous hour of the morning by Sherlock only just coming to bed, crawling under the covers and curling into a ball against John’s chest. Once he does, he is out almost instantly, dropping off into a level of unconsciousness just above comatose.
Even on the mornings after those nights, Sherlock is still awake first. Most mornings, John wakes up to Sherlock watching him intently. He feels slightly robbed, never getting to see Sherlock blinking awake in the grey light of dawn, until the day after the bomber in Sussex.
Sherlock spends two days in hospital, drugged to the gills, before they let John take him home. He is still on quite a lot of painkillers, which is probably why he sleeps so late the next morning. John hasn’t the slightest desire to wake him. He is waiting.
Nine minutes later, Sherlock yawns and half-opens his eyes. John smiles.
“I get it now.”
“Mm?” Sherlock rumbles into his pillow.
“Why you always get up first.”
It is a Sunday in October, and Sherlock has not had a case in six days.
He is pacing up and down the flat in his pajamas and dressing-gown and has been for forty-five minutes. John is just beginning to worry he’s going to wear a hole through the floor when he flops down onto the sofa with his hands over his ears.
“What is it?” John asks, with the patient air of a man familiar to this routine.
Sherlock squeezes his eyes shut and gasps, which is concerning. “It’s too loud,” he manages. “Inside my head.”
John grimaces. He does not possess quite the same processing capacity that Sherlock does, as he is often reminded, but he can sympathize a bit with how much can happen inside your head when it’s unoccupied. He pats the spot next to him. “Come on up then. Budge over.”
Sherlock glares at him suspiciously. “What are you going to do?”
“I’m going to help, you twit. Come here.”
Sherlock crawls over and flops down, half on John’s lap. He rolls his eyes and shifts them round, arranging them so Sherlock is sitting cross-legged just against John’s right leg and pushes his fingers into Sherlock’s curly hair, rubbing gently at his temples.
Sherlock gives a little sigh of relief. It's a promising sign, so John continues. While massaging Sherlock’s temples with his index and middle fingers, he presses his thumbs to the base of his skull where it meets his neck. This garners him a deep, satisfied hum, and he smiles.
“There’s a joke in here somewhere about picking someone’s brains.”
“Shut up,” says Sherlock, not at all unkindly. “Unless you want to recite a bit of the Fibonacci sequence for me. That would make everything absolutely perfect.”
“The...er, alright then. Zero, one, one, two, three, five...”
He makes it up to 1,597 before his mental arithmetic fails him and he forgets the number that came before.
“Sorry. That’s all I’ve got.”
“It’s fine. That was sufficient.” Sherlock is speaking as if half-asleep, or from far away.
John rubs his knuckles at the cords of muscle on the back of Sherlock’s neck. “The Fibonacci sequence?”
“Integer sequences are clean, particularly the ones remembered via calculation rather than memorization. The Fibonacci sequence is closely related to the golden mean, which is thought to be the basis for what humankind considers to be beautiful. It’s the mathematical proportion responsible for everything from Greek architecture to the popularity of certain celebrities. I find it fascinating.”
“I do know what the golden mean is. I’ve read The Da Vinci Code.”
“Let me do the honors. ‘Popular drivel,’ yes?”
“Something like that. Could we stop talking again? I think it’s quiet enough for that now, and I would like it.”
They stay that way for half an hour, John’s fingers working the tension out of the muscles of Sherlock’s neck and shoulders and back in silence, punctuated by Sherlock’s occasional rumbling hums of satisfaction.
“Top Gear. Telly night?”
“If I must.”
John smiles secretly as Sherlock snatches the large, soft blue fleece blanket off the back of the sofa, wraps himself up in it and tips his body sideways so he’s leaning against John, head on his shoulder in a way that should probably be more uncomfortable than it is.
“If I must,” John has cleverly deduced, is consulting detective-speak for “you’ve nothing on and are sitting still in one place, and I’ve nothing on and would like to be still for a while in the same place that you are.” If John asks, “Telly night?” and Sherlock responds merely with a deep, long-suffering sigh, that really does mean “if I must.” He quickly learns that the one must never be mistaken for the other.
John prefers the former. Curling up with a warm, lanky, dubiously sociopathic detective makes for a much more pleasant evening than sitting on the couch alone, even if:
“Move your head. Your hair’s in my nose.”
“Oh, no you don’t--”
After a short bout of wrestling, Sherlock settles for sprawling across John’s lap like an oversized housecat, which is worth a long round of chuckling at the very least.
Lestrade does punch Sherlock when he finds out he’s alive. Sherlock looks so shocked, holding a tissue to his bloody nose, that John cannot stop himself from bursting into laughter. Sherlock glares at him from around the tissue.
“You won’t mind if I find myself less amused,” he snaps.
John wipes his eyes, still giggling. “Don’t mind me.”
Sherlock is still glaring reproachfully.
“Oh, cut that out,” John says, taking the tissue and dabbing at his nose. “Look, not even bleeding anymore.”
He tosses the tissue into a trash can, takes Sherlock’s hand, the one that isn’t all bloodied up, and brushes a fond kiss across the knuckles. Lestrade raises his eyebrows, but doesn’t comment.
They don’t let go until they’re back in Baker Street. The whole cab ride home they both catch themselves shooting glances at their hands and grinning. By sheer chance, they never do so at the same time, and never realize they are thinking the exact same thought for only the second time in their lives so far.
It happens at the breakfast table, as quietly as it began.
“Pass me the jam, would you?” John says.
Sherlock does so. As he hands the jar to John, their fingers touch briefly, John catches his eye, and they both smile. As John is spreading the jam over his toast, Sherlock shakes open the newspaper and chuckles to himself.
“What’s gotten you all pleased, then?” John asks.
“Nothing,” says Sherlock.
John shakes his head. “You are absurd, you know that? Categorically absurd.”
Sherlock grins. John smiles back.
After the one hundredth time they simultaneously realize they are in love, it doesn’t bear mentioning anymore.