Chapter One: Sherlock Provides a Demonstration

They've been living together for two months when John first catches him doing it.

John Watson is just finishing the evening's washing up when he hears an odd humming noise. It's deep and throaty, like something emanating from the big cats enclosure at the zoo. Whatever it is, it's hitting John's ribcage and making it throb. He drops a soapy mug mid-scrub and follows the feral rumbling into the sitting room.

There he finds Sherlock, lying on his back on the sofa, his interminable legs draped over the far armrest. His head is tilted upwards, and his throat is exposed and vibrating in the half-light. He's purring, and his toes are flexing languidly, as though conducting an invisible orchestra. Sherlock's hands are rooted in his hair, and he's stroking slow, gentle circles into his temples with the pads of his thumbs. John has to mentally admit that there's something sensuous in the way he's laying hands on himself, as though he were his own violin.

Sherlock lets his head drop to one side. "John," he says, not turning around to look at his flatmate.

"Hmm? Just finished tidying up." John hasn't, in fact, finished, largely because Sherlock blew up the dishwasher last week, but he's not going back to it now. He has no idea what Sherlock is doing, but whatever it is, it's more compelling than tea-encrusted crockery. He's hoping his interest is not too obvious as he plunks himself down in the red armchair to get a front-row seat.

"Deleting," replies Sherlock, in response to the question John has not asked.

He should be used to this by now, but Sherlock's casual intrusions into John's headspace still make him blink. "Oh," he says. "Right."

There is a silence. John gingerly lifts a coffee-stained issue of the Journal of Analytical Toxicology off a stack of magazines littering the floor. He opens to an article on metabolites in human plasma following the subcutaneous administration of cocaine, then knits his eyebrows and rubs a hand over his stubbled chin. He's giving his best impression of a man possessed by the spirit of scholarly inquiry and not, emphatically not, by a desire to scope out the man who sleeps downstairs, if in fact he ever sleeps.

"Go on," says John, with what he hopes is a particularly nonchalant hand wave. He fixes his pupils on the top of the page, where he can see the text whilst maintaining the ability to quickly refocus on Sherlock, should the need arise. "Don't let me stop you."

"Mmm. If you like." The words are delivered in a lazy, baritone drawl that goes straight to John's core.

If I like? Since when does he give a damn what I like? And since when have I wanted to suck off my male flatmate just for existing? Oh, right, since the day I moved in.

John doesn't have to look at Sherlock. He can hear him smirking. As soon as Sherlock goes back to touching his own head, John looks at him anyway.


Sherlock begins by inserting his fingertips into the hollows behind his eyes and above his cheekbones, just at the spot where the sphenoid bone meets the temporal. Slowly, with great precision, he traces patterns there – ellipses, spirals, figure eights. His lips part and he starts purring again.

No longer preoccupied with being caught looking, John just stares at him, taking all of him in. His long, lean body. The rise and fall of his chest. The way his dressing gown clings to his many angles and few curves. Sherlock often looks imperious or amused or penetratingly intelligent, but stroking his own head with his hands, he looks abandoned and loose-limbed and ridiculously fuckable. John actually chokes for a moment. Despite five years of medical training, he has just forgotten how to breathe.

Sherlock's eyes are closed and his head is lolling indecently on the sofa cushions. "Ohhh, yes," he breathes, then lets the purring resume. He runs his long, pale fingers through his dark mop of hair, and for a moment John thinks of a piano: white keys moving against black. At first, Sherlock is gentle, applying only enough pressure to stimulate the follicles. Then he works his way up to tugging, then clenching. By the time he's moved on to uninhibited fisting, John is blushing furiously and the hair on his own head is standing at attention. It's something that occasionally happens when he's excited. The last time it happened, he was in a jeep in Kandahar, and a Canadian colonel named Anna was blowing him in the back seat.

Oh fucking hell.

John takes a moment to do a quick self-check on his own sexuality. He first performed a differential diagnosis on his romantic proclivities at about age thirteen and found them to be robustly heterosexual. Setting aside the last two months, the intervening decades have given him no real reason to question these initial findings. He's able to tell if another man is handsome, in a theoretical way, but he would never make a move on one. Not when women are lovely and curvy and good-smelling and so very unlikely to detonate major household appliances.

And yet. There lies Sherlock, his T-shirt rucked up on one side from all the wriggling, one smooth-skinned, angular hip revealed, and John has to let his legs fall open just to restore circulation. He has never been harder in his life.

Then Sherlock's breath catches, and his fingers stop in mid-stroke. It's as if he's found something under the skin, something small and hard, like a marble or a bead. He bites his lower lip in concentration, just enough to redden it. John can see that Sherlock has found something he wants to delete, and he's going to go in after it.

John groans out loud. The Journal of Analytical Toxicology falls on the floor, contributing once again to the general debris. It is an understatement to say that at this point, John does not give a fuck.

Sherlock, for God's sake, you can't do that. You can't use your fingertips to reassign parts of your neural network that strike you as being "suboptimally configured." It's not anatomically possible. Sherlock…

Unlike his flatmate, John has practice in not saying everything that pops into his head, and he puts it to good use now. If he were to make his case against deletion, there is the slight but present danger that Sherlock would listen to his medical opinion for once and stop whatever he's doing and never try it again, at least in front of an audience. John decides that if Sherlock wants to test the limits of what biology will permit, he is damned if he, John Watson, is going to fight science.

Sherlock is applying more pressure now, his fingers gripping his temples. Then his fingers fly out and he thrusts his thumbs into the hollows above his cheekbones. He moans and begins rocking them in and out, skin dipping into skin, convex against concave. He is unearthly and strange and unimaginably beautiful, like an alabaster archangel who has crash-landed on the sofa, and the sounds issuing forth from that pearly throat are making John weak.

The fuck is he doing? He made it clear at Angelo's he's not even remotely interested in sex, and now he's giving himself … what, a skull fuck? A brain job? How is that even happening? John bites his lip so hard that it bleeds.

And now this particular symphony is coming to a crescendo. Panting, Sherlock continues to work his temples over with his thumbs. His eyes toss and turn behind closed lids, as though he's shipwrecked and dreaming. There's a fine sheen of sweat on the parts of his body that John can see – his sweet, white throat; his elegant hands; that damnable hip – and he's shaking all over. One of his legs falls off the armrest and on to the floor, but he doesn't seem to even know it's gone. He's lost, and he rocks his thumbs hard and fast.

Nnngh. Just fucking nnngh on a plate with crisps on top. Oh God, Sherlock…

Suddenly, Sherlock arches his neck, lifts his hips, crams his fist in his mouth (what, no, his whole fist?), shouts once, then, in front of his painfully aroused flatmate, falls back spent and boneless on the sofa.

John watches dizzily as Sherlock angles his head in his direction, then opens his eyes, pupils vast and black like a night without stars. The detective's chest is still heaving, availing itself of all the extra oxygen that has been freed up by the fact that John has forgotten to breathe again. "John," he pants. "John."

Once he gets over the shock of feeling his own cock leak pre-come in response to the way Sherlock says his name, John has the feeling, half-panic and half-giddiness, that the man in front of him is going to ask him if he has a cigarette. Or worse, make him go fetch a cigarette, probably from the pocket of his pajama bottoms. John's eyes stray to said pajama bottoms, which look surprisingly dry.

So…he didn't get off? Or he got off but didn't ejaculate? So many things that could be: retrograde ejaculation, inflamed prostate, stricture of the seminal vesicles. Or, erm, "overuse." Orgasming so often that there's no time for fluid to build up. Wait, how often…

"Would it help to remind you that my face is up here?" asks Sherlock, bemused. He maneuvers himself into a cross-legged sitting position. Now that's he's finished, he's all elbows and knees and points again and watching him sit up is like watching a piece of origami spontaneously evolve into something sentient.

"I'm just wondering if you're … all right. If you'd like a medical opinion, I could …"

"Yes, I'm sure you could," says Sherlock drily. "Thank you. I'm fine. I'm perfectly capable of ejaculating, just not via the sole stimulus of cerebral self-stimulation." Sherlock runs an exploratory hand over his left temple.

"Usually," he continues. His voice is like a chocolate-covered cello, and John starts choking again.

Please. For the love of God, do not engage in afterplay. Do not cuddle and caress the side of your head while murmuring sweet nothings to it for fifteen minutes to help it come down after sex, or I am going to have a heart attack in front of you, and as soon as you get your mouth on me to do CPR, I promise you, I will die.

"Yeah," says John, after swallowing a few times. "Of course. It's just … what was that?"

Sherlock gives the tormented groan of a genius who has been asked to repeat himself. "I told you, I was deleting. Look, we know what we know due to the pathways linking our neurons, yes?"


"And every time we learn something, new pathways are created, correct?"


"Well, most of the things we learn are rubbish. They are useless, irrelevant, or just plain wrong, John. Yet there our brains are, happily creating pathways in the service of all manner of junk; pathways that, metaphorically speaking, lead into a swamp or off a cliff or, God help us, into Anderson's apartment. Of course, if our brains were infinite in volume and in search speed, the irrelevancies wouldn't be a problem. Only the outright falsehoods would be an issue. However, the human brain is roughly the size of a cantaloupe. So if you discovered a method of removing all the unnecessary or dangerous paths from your cerebral real estate, thus freeing up space for more productive uses, wouldn't you apply it?"

"No," says John.

Sherlock looks at him curiously. "Why not?"

"Because human beings are not always able to recognize what is important. Sometimes what's important just looks irritating or frustrating or out of place. For example, what about you telling me my whole life story, inviting me back to Mrs. Hudson's, and then winking at me – which, by the way, is not an appropriate way to conclude an interview of a potential flatmate? What if I had just deleted that whole interaction as soon as it happened?"

"Then, presumably, you would still have access to a working dishwasher."

John picks up the Union Jack cushion and hurls it at him. It's a satisfyingly direct hit to the chest.

"Hmm, domestic violence," says Sherlock, having inspected the cushion for clues. "Could be dangerous."

"You'd best believe I'm dangerous," says John, folding his arms.

Sherlock mimes terror for two seconds before getting bored and sending the Union Jack cushion sailing back at the aggressor.

"So when you delete," John ventures, "do you always do it … like that?"

"Like what?" Sherlock inquires. John turns red as a pomegranate.

"Oh," says Sherlock, "the writhing and carrying on. No, I don't have to do it that way. I can be immobile and silent and fast, if I wish, although it helps to steeple my fingers. It's just … that's how I learned to do it first, and sometimes, it's interesting to go back to that."

John ponders the new information. "So you have other ways of reconfiguring your hard drive. And you chose this one…"

The detective tilts an innocent eyebrow heavenward. "For your benefit? Yes."