A/N: Characters do not belong to me. Never happened. Slashy slash slash. I just thought some smutty fluff would help soothe those Reichenbach blues.
Now John understood why they called it carnal knowledge. Once having had a taste for something, Sherlock couldn't settle for knowing just a little about it. He had to know everything. John had meant to just open a door and instead the entire bloody wall came down as every suppressed and frustrated sexual notion Sherlock Holmes had ever had since puberty came stampeding forth, demanding attention.
I've created a monster, he thought to himself for the hundredth time. But at the same time, he could hardly regret that one of the most beautiful, intelligent, and intriguing men he'd ever known thought that the sun rose and set in John's trousers. But good lord, the man was downright … frisky. John reckoned that the reasoning behind it was a muddle of things: pent-up sexual desire, Sherlock's obsessive need to conduct experiments, sheer curiosity, and well, perhaps genuine affection for the doctor.
They'd taken it fairly slowly at first, to give Sherlock time to get more used to the mind-altering experience of sexual arousal and for John to get used to the idea of being Sherlock's lover. The words "Sherlock" and "lover" didn't even seem to go together, but there it was.
And John had to admit he was enjoying his role as the more experienced lover guiding the way. The only time he'd been with a virgin was when he was a virgin himself as a teenager. He and his girlfriend at the time had deflowered each other in a fumblingly awkward but sweet encounter.
Sherlock was so beyond John in practically every way that it felt rather amazing to be on the other side for once. And to be the one to see Sherlock experiencing all of it for the first time. He was learning so much more about his friend/flatmate/lover. In spite of the seemingly ascetic lifestyle he led, Sherlock Holmes really was quite a hedonist. Having been forced to give up smoking and cocaine — two of his most beloved vices — he had taken up the practice of being sexual with typical Sherlockian intensity. He was frank and honest about it and asked John incessant questions, many of which John wasn't even able to answer without the help of Google (and naturally, Sherlock would whip out his phone and beat him to the punch). John's own sexual history was fairly bland. He'd had a handful of sexual relationships and a few one-nighters (usually when drunk and the sex had never been memorable) and everything had been fairly standard. "Vanilla" was apparently the term, according to Sherlock.
Not surprisingly, Sherlock was a curious and fearless lover. It was his request that they expand into anal play and John was more than happy to comply. That had been an unforgettable night, starting with them kissing and touching and when Sherlock was hard and his breath was coming in short, urgent gasps, John began to stroke his hole with a well-lubricated finger, causing Sherlock to shudder, intrigued and unused to the sensation.
"Relax, love," John murmured, kissing Sherlock tenderly before breaching him with his finger. Sherlock had shuddered again, groaning very softly, and then almost fell off the bed when John crooked his finger and brushed over his prostate.
"Dear God, what was that?" he'd exclaimed.
John chuckled. "You know exactly what that was."
"Yes," Sherlock had murmured faintly. "But I had no idea. Do it again, John."
And John had done it again. And again. By the end, he had shifted down and was enthusiastically sucking Sherlock's cock while fucking him with two fingers. If Sherlock moved back, he drove John's fingers in deeper; if he moved forward, he sank deeper into John's mouth. He was well caught and John used his fingers and tongue to bring Sherlock to the edge, then pull him back, then push him forward again. He did it again and again until Sherlock finally crumbled and begged him for release. After begging, he became incoherent, and that's when John pushed him all the way over and Sherlock literally sobbed with relief as he came, his entire body shaking as John swallowed him down.
John had slid back up to lay next to Sherlock, reaching out to wipe a tear from the corner of his eye. He'd never made someone cry from pleasure before. Sex with Sherlock made him feel powerful and virile in a way he'd never experienced before. It was intoxicating.
John had cocked his head, confused. "Excuse me?"
"I want you to fuck me now, John." Sherlock's fingers wrapped around him and John groaned softly. "You're hard and I want you to fuck me."
"But Sherlock, you just came and I want you to —"
"No," Sherlock interrupted, his voice calm and serene, a little muffled by the pillow, "it's the perfect time. I'm relaxed and stretched and it won't hurt nearly as much if you do it now. I want to feel what it's like. I want you to come inside me. Please, John. Fuck me."
So John had slipped a pillow under Sherlock's hips and knelt behind him, admiring the long length of Sherlock's back and those beautiful shoulder blades that were incredibly erotic to him for some reason. He slipped on a condom (Sherlock would later request he be tested and when John received the all-clear they did away with condoms altogether), lubed up, and petted Sherlock's lower back gently, then stroked his palm reverently over Sherlock's pert little backside. "Are you ready?"
"Yes, John. Do it now."
John had gently spread Sherlock open, lined himself up and slowly pushed inside, gasping at the sensation. It wasn't difficult because John had worked the muscle so thoroughly earlier, but still Sherlock was tight, so tight, and he fit John like a glove.
"Jesus," he'd gasped. "Oh god, Sherlock."
Sherlock had groaned softly as John had entered, letting out a shaky breath, but he was still able to take the piss. "Invoking the deities already, John? A good sign, I daresay."
"Shut up," John half-groaned, half-chuckled. "If I'd had any idea earlier what a hot little arse you had on you, we would have been at this much sooner."
"Really, John, I had hoped that at least a fraction of my deductive skills might have rubbed off on you by now," murmured Sherlock, groaning softly as John seated himself fully inside. "But clearly not. Now fuck that 'hot little arse,' if you please."
And he had. He'd kept his thrusts slow and deep, letting Sherlock feel every inch of him. Leaning over to kiss and nibble at Sherlock's neck and shoulders. Cradling the other man's slender hips in his hands and watching his cock sliding in and out of him.
Sherlock was too soon off his mind-bending climax to get it up again, but he had sighed and moaned in pleasure, learning to rock his hips in time with John's thrusts, and then to squeeze John with his muscles, working him from the inside. Driving John out of his mind until he shuddered and came, thrusting hard and fast into Sherlock, then collapsing over his lover's back, his chest heaving.
"Drat. I had hoped I could make you beg for mercy," Sherlock's voice was gentle and amused and a little breathless.
"Like you did earlier? I thought you said you never begged for mercy," John gasped.
"You lost the capability for speech after that. I think that counts for at least two instances of begging." He was referencing Irene Adler's irritatingly bold assertion and he knew Sherlock would pick up on it.
"It certainly does not."
"Is that a challenge, Sherlock?"
"Glad to see that you are not too terribly dull-witted after orgasm, John."