A/N: I had a blast writing this little oneshot, I hope you guys like it!

Enjoy!

The first time it happens, neither of them are expecting it.

It happens in the aftermath of a particularly exciting case, after they've both pounded up the stairs to the flat like rowdy schoolboys, still high on adrenaline and not quite thinking straight. It's when Sherlock finishes his breathless, excited deduction and John smiles and says "You're brilliant, you know that?" that Sherlock senses a tangible shift in the air. Call it a change in atmosphere or a lapse in judgment, but either way, something otherworldly prompts Sherlock to grab the sides of John's face and press a hard kiss to his lips. It's close-mouthed and makes a loud smacking sound when he pulls away, but the sensation thrums through his body like tremors of music nonetheless.

"What was that?" John asks.

"I don't know," Sherlock replies breathlessly, and does it again.

This time, John is ready and he tilts his head to the right and opens his mouth and their tongues tangle in a hot, wet mess of a kiss that sends red sparks straight down Sherlock's spine. Sherlock breaks away for a moment to indulge his conscience's annoying reminder that this is a Bit Not Good, but before he has a chance to voice his concerns, John puts both hands on Sherlock's arse and squeezes.

"You good?" John murmurs against his neck, his palms kneading and massaging and doing all sorts of distracting, wonderful things to Sherlock's bum.

"Hnng," he intelligently replies, turning his head so that their mouths messily collide once again.

Sherlock wonders, briefly, if they ought to talk about this—maybe figure out if this is the best course of action—but every time his dopamine-soaked brain surfaces long enough to form a thought, John's hands travel somewhere new or his tongue curls a certain way, so eventually Sherlock is forced to slam the door to his mind palace, hang a 'do not disturb sign' on the doorknob, and call it a day.

"Bedroom?" John pants, pulling away for half a second.

"Yeah," he replies, already dragging John down the hallway.

After that, it's just a noisy jumble of limbs and hastily shed clothing, a few frantic slides of skin against skin, and a considerably small amount of conversation.

Sherlock figures they can talk about it later.

Later comes, and they still don't talk about it. It isn't that they're actively avoiding the subject, per say, it's simply that there are too many other things going on with cases and experiments and everyday life to bother to sit down and have a deep conversation about what Sherlock assumes was a one-time thing.

They don't act differently around each other or behave awkwardly, either, which Sherlock thinks is quite a relief. Things are so utterly unchanged by that one, arbitrary night that Sherlock begins to forget it even happened. In fact, he might've let it slip through the cracks of his mind palace entirely, had John not walked into the sitting room a week later, wearing only a towel.

"Sherlock, did you move my hairbrush?" John asks, scrubbing a hand through his wet hair. His other hand is holding onto the white towel around his waist. "It isn't in the cabinet where I left it."

Sherlock drops his book and momentarily forgets how to speak.

John's skin is all sweet-smelling and wet from the shower, steam rising off his muscled shoulders and arms like smoke on a burning coal. The towel isn't all that long (thank the gods), so Sherlock is treated to the lovely sight of John's shapely calves and strong ankles, slick with leftover bath gel and water. His wide chest is flushed pink from the heat and his tan skin looks positively golden against the white material around his waist.

"Sherlock?"

Sherlock is struck with the sudden, inexplicable urge to lick the drops of water off John's hipbones.

"Earth to Sherlock?" John tries again, waving his hands about.

Almost as if on autopilot, Sherlock gets out of his chair, strides towards John, crowds him against the wall, and kisses him so thoroughly that John actually goes weak in the knees and falls against Sherlock's chest.

"Jesus, Sherlock," John groans, taking Sherlock's collar in a fist and hauling him closer. "C'mere."

An hour later, the towel, along with Sherlock's shirt, trousers, and pants, end up in a heap by the bedroom door and John finds himself in need of yet another shower—though, Sherlock is fairly certain John doesn't mind terribly.

The next time it happens, they leave three rounds of empty glasses and two overturned barstools in their wake.

"I'm—hic—a bit smashed," John confesses as they stagger out of the pub, John somehow missing a shoe and Sherlock wearing a party hat that neither of them remember him donning.

"Mm, there's something-whatever percent of alcohol in our bloodstreams right now. Isn't that a wonder, John? I have tequila in my veins as we speak," Sherlock observes, tripping over his words a bit.

"Mm. Hey, guess what," John slurs.

"Not enough sense left for a guess. What is it?"

"I'd like to snog you," John announces, throwing an arm around Sherlock's waist and tugging him flush against his side. The two stumble along the pavement, Sherlock's coat billowing around the both of them like a cloak.

"Well there's n' alleyway," Sherlock points out. "And I really, really wanna kiss you too, John."

"Oh yeah?" John grins, and in the moonlight, the smile looks positively predatory. Sherlock watches with growing fascination as John's blue irises become eclipsed by his black, dilated pupils. He's only partially surprised that his own desire skyrockets at the sight, and he's even less surprised to find himself breathlessly replying:

"Now."

In the next moment, John grabs the front of his shirt and pushes him against the brick wall of the alley, his mouth nipping deliciously at Sherlock's neck while his hands dive into the coat and wrap around Sherlock's waist, pulling the two of them impossibly closer. Heat shoots straight to his groin as John licks a long stripe down his throat, pausing briefly to suck bruises into his pale skin and bite gently on his earlobe. Sherlock all but dissolves into a puddle.

"J-John," he murmurs against John's lips. "How strong are you?"

John sucks Sherlock's bottom lip into his mouth and tugs slightly, pulling a long, low groan from the detective. "Pretty strong, I dunno," John answers absently, his focus resting entirely in tasting ever last centimeter of Sherlock's mouth.

"Strong enough to hold me up?"

John stops sucking at his lip and pulls back to raise an eyebrow at him. Still panting, he asks, "Why?"

Equally breathless, Sherlock simply replies, "Friction." And, thankfully, John gets the idea.

"Hell yes, I can," John growls, cupping Sherlock's bum and using the momentum of Sherlock's jump to get the detective's legs firmly around his waist. Experimentally, John presses him harder against the wall and thrusts his hips, and they both groan at the sensation of his lower half grinding deliciously against Sherlock's.

"Jesus, Mary, and Joseph," John wheezes, tightening his grip on the undersides of Sherlock's thighs. "I think I've found heaven."

They still don't talk about it, but at this point, it doesn't seem terribly important anymore. They end up shagging their way through most of the alleys in London, a decent number of bathroom stalls at local restaurants, and nearly every room of the flat, save for the kitchen because that would be unsanitary (at least according to John). On more than one occasion, Mrs. Hudson drops a sly comment and a giggle about all the "ruckus she's been hearing upstairs," which makes John go red and Sherlock puff with pride.

All in all, Sherlock thinks it's a fairly satisfying arrangement.

"Sherlock? Hello, earth to detective! Are you even listening?" Lestrade asks in exasperation, slapping a stack of files on his desk.

"Of course," Sherlock lies easily.

"Oh yeah? Then repeat what I just said."

He and John are currently seated in Lestrade's office filling out boring paperwork from their latest case, and, unfortunately, while Lestrade was explaining their tasks in terms an infant could comprehend, Sherlock was quite happily remembering the perpetually empty closet on the third floor—which then led to the inevitable conclusion that he and John ought to take advantage of it immediately. Thus he hasn't the slightest idea of what is going on at the moment, least of all what Lestrade just said.

"Something or another about the case," Sherlock guesses.

"Christ, Sherlock, would it kill you to bloody listen to me for once?" Lestrade cries.

He shrugs. "Probably."

With that dealt with, he turns to John to discuss more important matters. "John, we were meant to check something on the third floor, weren't we?"

John glances at Lestrade and then frowns at Sherlock. He's right in the middle of saying Not that I'm aware of, when Sherlock pointedly places his hand on John's crotch and squeezes—an action that just barely manages to avoid Lestrade's notice.

After that, John quickly changes his tune.

"Oh, yes, I do believe you're correct, Sherlock," John agrees, his voice slightly pitchy. "Er, yeah, sorry to run, Greg, but we've got important business on the third floor. Very important business."

"The third floor? But isn't that the rookie center for—"

"Yes, and we are needed there desperately," Sherlock interrupts, already heading to the door with John in tow. "Text us if anything else comes up!"

"But you lot haven't even finished filling out the first bloody paper of the—"

"Have a good one, Lestrade!" John calls from over his shoulder as Sherlock tugs the both of them out the door and into the hallway.

…

An hour or so later sees the two of them sitting on the floor, leaning against the towering shelf of cleaning products and towels in the old janitor's closet, shoulder to shoulder and still naked.

Well, somewhat naked; Sherlock's topless and John's in his pants. Unfortunately, he could not convince John that going entirely starkers was a good idea—"What if someone opens the door, Sherlock? Or what if a criminal comes in here and attacks us? I can't fight someone off with my precious bits flopping about!"

And as unlikely as he found that scenario, Sherlock had no desire to put John's precious bits at risk, so he resigned himself to T-rated nudity and moved on.

"You know what?" Sherlock says, lifting his head from John's shoulder.

"Hm?"

"This is rather amusing."

"What is?"

"You know, us being in a closet and all. Fairly ironic."

"Hey," John protests, "I am not in the closet and I am not gay."

Sherlock rolls his eyes. "Yes, I'll speak on the behalf of the entire city of London and say that we know, John. You've certainly announced it enough times."

"Well, I'm not," John huffs.

"Fine. But I must say, a perfectly straight man would not have engaged in the activities that just took place," Sherlock reminds him with a smirk.

"Oh hush, you git. It's not my fault you're bloody attractive," John retorts, playfully swatting at Sherlock's shoulder. "Bisexual it is, I suppose."

"Actually, John, that's incorrect," Sherlock replies seriously. "While you are not homosexual, I believe you are definitely Holmes-sexual."

He does a decent job of keeping a straight face, but despite his best efforts, Sherlock can't hold the expression for long and a rather undignified snort escapes him almost immediately.

John just looks at him in amused disbelief. "Did you spontaneously revert back to a nine year old when I blinked a few seconds ago? I mean really, Sherlock? Puns?"

Sherlock, untroubled, continues chuckling. John eventually cracks a smile himself, and the sight of it is so lovely that Sherlock places a spontaneous kiss against the side of John's face.

"Yes, really. Though if it helps, I'll admit I am 100% John-sexual."

There are a few beats where they remain entwined with each other, John occasionally running his hands through Sherlock's curls and Sherlock nuzzling his face lazily into John's neck. It's peaceful and intimate in a way Sherlock has never experienced, and it leaves a warm sensation buzzing in his chest.

"I just realized something," John says after a moment.

"Hm?"

"If I'm Holmes-sexual," John continues, "then that means I'm attracted to all Holmeses, right? Including Mycroft."

The very mention of his brother in a sexual scenario makes Sherlock uncomfortable in ways that might inspire weaker men to burn cities. "Nope," he snaps, standing up and frantically dressing. "Do not say Mycroft's name when I am naked or when there is any glimmer of intercourse on the horizon. Understood? Christ, I need to get out of here, I'm starting to develop very disturbing mental images."

"That's what you get for making a pun," John chides, buttoning up his shirt. "Now you've learned your lesson."

"It'd be a shock if this episode hasn't shriveled my sense of humor entirely," Sherlock shudders. "Now can we please leave? I'd rather my libido didn't permanently disappear as well."

Nearly a month later, they finally talk about it.

"Sherlock," John says one evening while he reads the paper, "I've been meaning to ask you something."

"Well on with it, John, no need to hold me in suspense," Sherlock replies distractedly, adjusting the slide under his microscope.

John ruffles the paper and folds it closed. "What are we doing?"

"I am examining coagulated saliva and you are pretending to read the paper while you attempt to articulate whatever matter is pressing on your mind."

"I'm talking about all the physical action that's been happening lately, Sherlock!"

"Oh, that."

"Yeah, that," John retorts.

"It's really not a big deal, John," Sherlock dismisses, returning to his experiment.

Because it isn't. The simple facts are: he loves John and he loves having sex with John. Both are as obvious as the day is long.

"Not a big deal?" John repeats, dumbfounded. "Sherlock, we had sex in a bloody alleyway last weekend. And then a few days after that, in a closet at Bart's. Now I could be wrong, but I think that qualifies as a big deal!"

"John, it's hardly impressive in comparison to last Tuesday," Sherlock replies reasonably. "Remember? We were in that stall at Angelo's and you—"

"Yes, I was there," John cuts in pointedly. "No need to repeatit."

"Fine," Sherlock concedes impatiently, eager to move on from this subject and continue his experiment. "What did you want to say about it?"

John ignores his snappish tone and calmly inquires, "Well, for one, why do you keep doing it?"

"Last I checked, frottage, oral sex, and digital sex require two parties, John. So I do not "keep doing" anything, at least not on my own."

"God, can you not call it that?" John groans, covering his eyes with the heels of his palms. "It sounds too bloody technical. Let's just call it sex, alright? Or if you really insist, hooking up."

In response, Sherlock takes off his goggles and gives John the driest look he can muster. "Can you really imagine me saying 'hooking up' in any context? I'd prefer to call it what it is but I suppose if you'd like to dance around the terminology of it, then fine. Sex it is."

John rolls his eyes. "You can impress me with your attention to detail later, Sherlock, but for now can we skip the technicalities? Just answer the question, please."

"Very well. I 'do' it because it's highly enjoyable and passes the time," Sherlock answers truthfully.

Apparently that answer isn't a good one.

"Passes the time? Passes the time? So, what, you like to have sex because otherwise you'd be bored?" John cries, sounding both indignant and offended. Sherlock gets the impression that he really should have responded with something different.

"The nerve!" John mumbles to himself, making a point of whipping the paper open again and pretending to read.

"John…"

"Nope! If that's all it is to you, then you can say goodbye to touching of any sort. I hope you got your fill last time because you are never getting anywhere near these pants again."

Nope, this is definitely not going the way he would like it to.

"Wait, now hold on just a minute, John," Sherlock says, jumping off his stool and rushing into the sitting room. "What did I say? Why was that the wrong answer?"

"You just admitted that we're only fooling around because you have nothing better to do! That depreciates the act, Sherlock! Takes away all its importance! And if you don't care about it, then neither do I. Unfortunately, I can't distance myself from things like you, so the only solution is to stop having sex altogether."

"No, John, that is not what I want," Sherlock insists. In a moment of horrid panic, he imagines going back to the ways things used to be, when John dated a handful of empty-headed women each month and Sherlock sourly abstained from physical activity as a whole, on the principal that if he couldn't have John then he'd settle for nothing.

Christ, no.

Distressed, he falls to his knees in front of John's chair and looks up at him with desperate eyes. "John, I did not mean it in that way. Of course it means a lot when we have sex," Sherlock says. "It's fun, exciting, and deeply profound. I love you, John. Hell, I would've thought that was obvious by now. Everything we've ever done together, from casework to sex, has been unimaginably important to me. I'm simply not accustomed to explaining my emotions so directly. I suppose I just assumed that my true intentions bled through implicitly. I…I apologize for making you think, even for a moment, that what we've been doing hasn't been significant."

John looks at him for a few beats, then sighs, begrudging fondness and affection once again coloring his features. "You're a git sometimes, you know that? But bloody hell, I love you anyway."

Sherlock thinks on this for a moment. "We love each other?"

John's eyes crinkle up in a smile. "Looks like."

"So…does this mean we're okay?"

"Of course."

"And we can have sex again?" Sherlock asks hopefully.

John chuckles. "Yes, please."

"Splendid."

Fondly, John pets Sherlock's hair back from his forehead, his fingers tangling deliciously in the detective's dark, unruly curls. "Just out of curiosity, though: why didn't you tell me all that in the first place? Would've saved a lot of trouble."

Sherlock considers formulating another deep, well-thought out response, but then it occurs to him that he's still on his knees in front of John and the ban on sex has been officially lifted.

Probably time for a bit of celebration, right?"

"Because, John," he says with a smirk, as he leans forward and takes John's zipper between his teeth. "I'd much rather show you."

And Sherlock is pleased to find that John is more than happy to cooperate with a hands-on demonstration.

A/N: Thanks for reading, everyone! Please let me know what you think, feedback is food for my writer soul! :)