Sherlock's "not noticing" lasted right up until John clipped the handcuff around his right wrist. The notes slid away in a discordant glissando, then died entirely as John tugged Sherlock's arm - still holding the bow - down to the small of his back. Sherlock didn't fight, not really, but neither did he passively allow John to pull his other wrist down and handcuff them both together. The result was a cautious scuffle - careful not to make Sherlock drop the undoubtedly expensive violin - and, eventually, a sharp stomp of John's boot heel to the top of Sherlock's right foot. Sherlock jerked forward, which gave John enough time to snap the second cuff closed.

"I don't see what the fuss is about," Sherlock said. It would have sounded supercilious, to anyone except John. The faint tensing of his shoulders told a different story, though - Sherlock was interested. Probably more than just interested - intrigued. The highest praise Sherlock ever gave anything. John tugged on the handcuff chain, just enough to throw Sherlock off-balance for a second before he could right himself.

"We did go over this." John kept his voice firm, which was at odds with the gentleness with which he removed the bow and violin from Sherlock's grip and laid them on the desk. Sherlock gave John a surprised look of approval when he carefully loosened the bow strings before putting both away in the case - John may not have any experience with stringed instruments, but he'd seen Sherlock conduct this little ritual countless times and it wasn't exactly hard to mimic. Violin secured, John turned and resumed a military stance - hands behind his back, head up, chest out, assessing Sherlock carefully. "You've been remiss," he finally declared.

Sherlock licked his lips. "I don't see how."

"Yes, I rather suspect you don't." John stalked around Sherlock in a narrow circle, not quite coming close enough to touch him but definitely close enough to notice how Sherlock's breathing quickened. He caught Sherlock's eye and gave him a long, impersonal stare as he passed, starting a second round. And saw-

"Oi, I did warn you."

Sherlock's fingers - already busy at work trying to manipulate the handcuffs' latch - stilled their motion. John wasn't fooled, though, just pulled the duct tape from his pocket and swiftly extracted a long strip. He wrapped Sherlock's hands separately, balling them into fists and then plastering them with several lengths of tape apiece, until they looked more like wads of bandages than hands. John did have a pair of safety scissors tucked down inside his waistband, and all that tape would probably be a bitch to get off later, but right now there were more important things.

Like bullying Sherlock backward, one threatening step at a time, until his calves bumped into his armchair. Sherlock kept his back straight and his head up, kept his eyes locked on John's, but that didn't stop him from slowly shuffling backward as John advanced. Until John was able to put out an arm and shove. Sherlock overbalanced into the seat easily.

Neither of them spoke. They didn't need to. It was rather nice, actually, to have the negotiations and the consent out of the way upfront for once - John was used to having to stop, talk through things a step at a time, and there was definitely something to be said for seizing the moment. Or whatever else he wanted to seize. Which, at this particular moment, was Sherlock's ass.

So he did, insinuating his hands around the sides of Sherlock's hips and grabbing a double handful of Sherlock's lean arse. Sherlock jerked, hips pistoning upward, and he drew in a sharp breath. His mouth opened-

"No." John leveled a glare at his flatmate. "Unless the next words out of your mouth are either "I'm sorry, John" or "please let me go," you are going to keep your maw shut and you are going to take whatever I damn well feel like doling out. Is that clear? Don't speak, just nod."

Sherlock swallowed hard and nodded, eyes wide.

"Good." John gave his arse another squeeze, then pulled back just far enough to reach for the coiled rope he'd left at the near edge of the desk. Sherlock's armchair didn't present much of anything useful to tie him to, which was a minor problem, but it was really more the principle of the thing anyway. John considered, then turn and plopped his weight down on Sherlock's lap to hold him steady while he untangled the knot he could have sworn hadn't been there five minutes earlier. Sherlock moaned softly and shifted his hips again, but didn't object.

The angle was awkward, but there was something rather thrilling about leaning down to tie Sherlock's ankles to the chair legs. The motion called attention to his own arse, practically put it on display not a foot from Sherlock's face as he leaned over double to secure the rope. John wasn't usually a vain man, but he kept fit on purpose - it was safer, for one thing, what with all the chasing criminals and whatnot, and for another it made everything a lot easier when it came to catching women's attention. Or flatmates', it would seem. Sherlock sucked in a shaky breath and let it out slowly, not even bothering to kick when John's fingers closed around his ankles and cinched the rope tight. Mission accomplished, John sat back up and deliberately ground himself backward into Sherlock's groin. He could already feel Sherlock's hardness digging into his pelvic bone.

"What are you-"

"Nope," John interrupted, reaching back to grab the base of Sherlock's jaw in a pinching grip and shocking him into silence. "You. Don't. Get. To. Talk."

Sherlock opened his mouth again-

"On your feet." John jumped up, already missing the warmth of Sherlock's body heat against his back, but this would be oh so much better . . . He lunged forward, grabbed his own armchair, dragged it closer, and turned it around so the back was almost up against Sherlock's knees. "Bend over my chair, mouth shut. I don't want to hear it. You can't follow my rules, you get spanked. You keep making noise, you get spanked harder. Is that clear?"

". . . Yes," Sherlock mumbled.

John grabbed the nape of Sherlock's neck and yanked, helping him get the leverage to rise to his feet. "That should have been a nod," he said in a low tone. "What, you want to have to stand for the next week?"

Sherlock's eyes widened, but he shook his head. And kept silent. And leaned forward so the back of John's chair was pressing into his chest and his gorgeous arse was perfectly, blessedly accessible.

John smoothed a hand down Sherlock's spine, nape to tailbone. Sherlock trembled but made a valiant effort to hold still. John continued the motion, smoothing over Sherlock's arse and down to grip possessively at one cheek. And then, with no warning, he let fly with a decisive smack.

Sherlock did jump at that, gasping and stiffening his entire body. John repeated the motion on the other cheek, not so hard it would bruise (especially not through the fabric of Sherlock's trousers), just hard enough to get his attention. And from the way Sherlock's erection was tenting the front of his pants already, it was working.

"I'm going to take these off now," John said conversationally. "Next two are with just your pants on, then the two after that are bare skin. Think you can handle that? Nod for me."

Sherlock nodded, a tiny whimper escaping his throat. Overwhelmed, but in a good way. John undid the button and worked Sherlock's trousers off his hips, letting them pool around his knees where the edge of the armchair stopped their downward progress.

And, not terribly surprising to see, Sherlock shirtless and wearing only a pair of black pants was even more sexy than Sherlock in a put-together suit. John caressed Sherlock's arse again, more roughly this time, running his palm from the small of Sherlock's back down to the tops of his thighs and back. He did it a second time, letting his middle finger dig deeper between Sherlock's legs, pressing forward to run along the skin just behind his balls through the thin fabric, and Sherlock let out an honest-to-goodness mewl. John withdrew his hand and brought it down again in two more symmetrical smacks, evenly spaced from Sherlock's midline and just far enough from the first spankings to not cross that line between good-pain and bad-pain. Sherlock's head was hanging limply now, eyes closed and breath coming in tight gasps. John took a moment to savor the sight.

"You ready for the last two?"

Sherlock hesitated, but finally nodded. John slid his hands around to the sides of Sherlock's ribcage, then dragged them downwards over his hips, taking the pants with them. One last twitch to get them free from Sherlock's erection and then Sherlock was beautifully, gloriously naked, arse already a bit red and raw and practically calling for John's attentions.

But an oblique side angle wasn't good enough for this - he needed something better. Luckily, Sherlock's armchair had a wide base and a low back. John carefully shed his own boots, socks, trousers and pants, and clambered in to seat himself directly behind Sherlock, his legs insinuating themselves between Sherlock's spread knees and his face directly in line with Sherlock's arse.

And fuck, it was worth the less-than-graceful contortions necessary to get himself there, because the view was amazing. Sherlock's arse was as pale as the rest of him, other than the nicely pink patches from John's palm. The ropes kept Sherlock's legs just wide enough to spread his cheeks, revealing all the glorious detail in between. And positioned at exactly the right level . . . John couldn't resist leaning forward and delivering a long lick up that crack.

Sherlock's head snapped up at that. John could practically hear the gears in his brain turning as he tried to absorb the sensation, tried to fit it into whatever mind-palace version of John he carried around in there, but John was having none of it. He palmed the taut muscles of Sherlock's arse in both hands, drawing them further apart, and lowered his head again.

The longer he worked, teasing at Sherlock's sensitive flesh with his tongue, the more Sherlock writhed. It started slowly, little twitches and pants, but in less than a minute Sherlock was squirming as far as the restraints and the awkward positioning allowed and was breathing in great, hoarse gasps. It was beautiful. John hadn't even touched his cock yet, hadn't given it the slightest bit of attention, but precome was already dribbling out and trailing down to mix with the sweat glistening on his bollocks. John narrowed his focus to that single hole, darting little flicks and flat laves and finally a slow, stiff thrust which had Sherlock groaning a litany of something that could have been curses and could have been a prayer.

John drew back and blew on Sherlock's damp skin. "No talking," he said, and loosed a firm smack on Sherlock's right cheek, just above where it met his thigh.

Sherlock almost managed to swallow his shout.

John massaged the skin with his palm, kneading the pain into what he knew would be a dull ache for at least the next twenty-four hours. And then repeated the performance on the left side. Sherlock managed to keep silent for that, although his whole body tensed at the blow.

"Remember your words," John said. "'I'm sorry, John,' or 'please let me go.' Those are your choices."

Sherlock whimpered.

And suddenly John didn't want to wait anymore. He withdrew the small packet of lube from his breast pocket - half the reason he'd kept the shirt on in the first place, to have that last little surprise - and managed to get it open on the first try. Sherlock couldn't see him, couldn't see what he was doing, and so it was a surprise when John's slick fingers slipped between his legs and pressed into his perineum.

"Nngh." Sherlock rocked his hips backward, desperately seeking more friction, but John kept the rest of his body purposely out of reach. And still didn't touch Sherlock's cock, just ran his fingers over the insides of Sherlock's thighs and slicking the base of his balls until Sherlock was blindly twisting, sobbing, just on the verge of begging for more. Only then did John put his hands around Sherlock's hips and guide him back down into his chair. And into John's lap.

Everything lined up perfectly - Sherlock's pants and trousers kept his knees nearly together and John was slouched forward a bit, so when Sherlock sank back, John's cock slipped perfectly between his lubed thighs. They groaned in unison at the sensation. John squeezed another dollop of lube into his right hand, then brought his arm around so the very tip of Sherlock's erection was just barely nudging into his clenched palm.

"This part is up to you," John growled into Sherlock's ear (or as close to it as he could get, given their relative positions). "You move forward, you're fucking yourself on me. You move backward, you're also fucking yourself on me." He thrust his hips in a single, careful stroke, letting the tip of his own cock push upward to brush against the underside of Sherlock's balls. "You have enough stamina, your thighs and abdominal muscles may last long enough for you to come. And if not, my slick, warm hand will stay just out of reach. You want this, don't you? Want to fuck yourself forwards and backwards between my cock and my fist?"

Sherlock nodded frantically.

"Then move. Find yourself a nice little rhythm."

It was harder for Sherlock than John had expected, primarily because with his wrists handcuffed behind his back and his ankles tied to the chair, he had almost no leverage. He had to lean forward almost double to be able to raise his body at all. He caught on quickly, though, and by the third or fourth thrust they had a smooth system: Sherlock thrust slowly forward into John's clenched fist, stomach and arse and thighs quivering, then he collapsed back down and John's cock would slide between his tight thighs and jolt his bollocks with a teasing hint of a stroke. And then he'd do it again. And again.

As John anticipated, Sherlock's much-abused muscles gave out before his cock did. Sherlock managed one last, pitiful half-lift, then sank back down into John's lap and hung his head in defeat.

"Words, Sherlock," John murmured. "Something you want to say?"

Sherlock licked his lips, panting heavily. "I - I'm sorry, John. Fuck. Please, just - I'm sorry, please let me come, John, please. I'm so close, I just can't - I'm sorry I'm sorry I'm sorry-"

John pressed a kiss against the sweaty skin of Sherlock's back and made soothing noises into the hollow of his shoulderblade. "You'll promise not to do that to me again?"

"I promise," Sherlock cried. "I won't ever - just please, let me-"

John nudged his hips upward at the same time he tightened his fist and swept it down to squeeze around Sherlock's aching erection. Sherlock sucked in a gasp of air and lost it again on a plaintive whine. John repeated the motion, closing his own eyes against the tight sensation of Sherlock's slick thighs and balls against his cock, of Sherlock's bony hips digging into his own, of Sherlock's weight pressing down into his lap.

The real catalyst was the noises, though, the sounds of Sherlock on the edge. Desperate whimpering, involuntary groans and exhalations and the way Sherlock was so obviously trying to hold on, trying to fake some modicum of control, and was so obviously failing. Spectacularly. John sped up the timing of his thrusts, his hand slick with lube and precome, adding a bit of variation in the pressure as he worked between Sherlock's shaft and the head-

Sherlock came apart the same way he pled - messy, frantic, without any finesse whatsoever, and so damn hot John could feel tears prickling at the corners of his eyes. Two thrusts later and John came, too, adding his own contribution to the liquid spattering Sherlock's bare chest.

They sat there, panting, for several long minutes. Just trying to get the world back to its normal hues. Sherlock rested his cheek on the convenient back of John's armchair, his dark curls plastered to his forehead and his eyes closed. John leaned back, letting his own head loll against the cushions, and struggled for something to say.

In the end, there was no need. They disentangled themselves by silent mutual consent. John found the safety scissors in his trousers pocket and freed Sherlock's hands, Sherlock did indeed get the handcuffs off with almost no effort whatsoever, and both of them worked to untie Sherlock's ankles and put their clothing to rights.

"So that happened," John finally said aloud.

Sherlock grunted.

Which was . . . not acceptable. "Sherlock," John said, the warning clear in his tone. "You don't get to be aloof about this. Not today."

Sherlock pulled his phone out of his pocket and pointedly said nothing.

Of all the . . . "Fine. Let me know when you're done filing or deleting or whatever. But we do need to talk." John fastened his zip enough to make it to the loo without having to actually hold up his trousers. Bloody berk, thinks hes a robot, locks his emotions away, it's plain as day he has them, this wasn't just a bloody lark-"

Ding. Ding.

John pulled his mobile out of his pocket and stared at the two text alerts. From Sherlock. He thumbed the phone open.

Results: Hypothesis conclusively confirmed. Sherlock Holmes resolved to be less of a berk in the future, in hopes of further experimental trials. -SH

Conclusion: Repeated trials necessary to assess efficacy of stimulus and possible variables in design. Suggest next trial in Sherlock Holmes' bedroom, for increased maneuverability. -SH

John stared at the phone. And slowly his expression transformed into a grin.

Well then. If it's for science . . .

He exited the bathroom and turned left, toward Sherlock's now-open bedroom door.