The shocked expression on Sherlock's face was absolutely worth any embarrassment John might have expected to feel. Sherlock looked absolutely pole-axed, like he hadn't even vaguely allowed space in that magnificent brain of his to plan for an eventuality in which John said yes. In his astonishment he let his mouth fall open, though, so John didn't have to imagine very hard to picture what the man would look like when his face was stuffed with John's cock.

Even once John had his trousers open and his boxers tugged down and his cock out free, Sherlock still took a minute to come back to himself. He did close his mouth, eventually, a sharp exhale and the click of his jaw snapping shut and then that intense gaze flicking from John's face to his erection and back again.

"I meant what I said about choking," he murmured aloud. "If you want to use my mouth like that, I don't mind."

Prat. "I'm not going to be an arse like that, Sherlock."

"Just alerting you that you may if you wish." Sherlock glanced up at John's face one last time, then inhaled deeply and practically impaled his throat on John's cock.

"Fuck." John had assumed Sherlock's bravado was more or less just foreplay - there was an art to sucking off someone as big as he was, no question, and even if Sherlock had plenty of theoretical knowledge (and John had no problem believing that), there was no substitute for practice. Sherlock seemed to be determined to turn theory into practice pretty damn quickly, though, licking and sucking by turns. He truly was going down far enough to choke himself, for John to feel the head of his cock ram up against the ring of muscle at the back of Sherlock's throat, and John didn't realize he was yanking on Sherlock's hair until the inky curls were already threading between his fingertips.

Sherlock moaned softly and tried again, attacking from a slightly steeper angle. His hands slid up John's legs and along John's bare thighs, fingertips tracing John's femoral artery (by feel, surely?) until Sherlock finally skittered them up the last few inches to tug and caress at John's bollocks with one hand and fondle the base of his shaft with the other. It was . . . well, beyond good, at any rate.

"You weren't - holy - you weren't lying," John gasped. "Where the hell did you learn to do this?"

Sherlock pulled off and looked up at him through his eyelashes. Not intentionally coy, just naturally bloody gorgeous. John felt another shot of no seriously, how the fuck did I get here? race through him. He slid his fingers deeper into Sherlock's hair, massaging Sherlock's scalp, and was rewarded with a husky moan.

"It's a valuable skill," Sherlock murmured. "Research, of course."

"Holy hell." God, even Sherlock's voice - low and raspy, like he'd been smoking again. Or like he'd just had a gigantic cock crammed down his throat and it was still a bit sore.

Sherlock seemed undeterred, though. "Do it," he urged, and leaned in to touch the very tip of his tongue to John's slit. His left hand was still massaging John's bollocks, barely-there light and teasing, but his right was sliding down to free his own cock from his pants and trousers. "Fuck my mouth, John. I love the way you feel on my tongue. All of you in there, as much as I can take, so much I can't swallow or breathe or-"

John yanked him forward by the hair and shut him up. Thoroughly. Bloody git had asked for it, hadn't he? Judging from the bone-shaking guttural moans coming from Sherlock's throat, he approved. More than approved, looked like - Sherlock's right shoulder was moving in a familiar rhythm, twitching up and down as he jerked himself off. Over me. Over sucking my cock. It should have been at least a little odd, watching another man wank, but John couldn't summon even a tiny bit of heterosexual panic at the sight. It was bloody hot, actually. John tilted his hips a bit, deepening the angle at which Sherlock was engulfing him, and slid his good leg forward.

"Rub off on me," he commanded, letting that tiny thread of I'm straight and I don't do this vanish from his brain. Sherlock wanking was too bloody amazing to miss. "I want to feel you."

Sherlock paused - surprised, or just letting the demand percolate through the fog of his arousal? - but then he shifted his weight so he was kneeling with one thigh on either side of John's shin and his oh god it's RIGHT THERE cock was pressed up against John's leg. It was hard to see, what with Sherlock's rapidly bobbing head in the way, but John wasn't entirely surprised to feel Sherlock's other hand abandon wanking and come up to splay against the skin of his inner thigh instead. There was no need to ask whether Sherlock was getting off on this - the shift of his hips back and forth and the choked moans continually vibrating John's erection were clues big enough that even John, with his merely ordinary powers of observation, couldn't miss them. That didn't even take into account the strange heat of Sherlock's erection pressed against John's shin. Probably leaving a wet spot on his trousers. Like it mattered.

"Mmmph." Sherlock groaned, long and low, then held John deep for what felt like forever. Christ, it's like he doesn't even need to breathe. For all John's experience with the dating scene, he could count on one hand the number of women who had managed to actually fit so much of him in their mouths - and none of even those few had enjoyed it half as much as Sherlock seemed to. John tightened his grip in Sherlock's curls - prompting the man to go practically boneless against him - and made a peremptory attempt at tugging him off.

"Gonna come," he warned.

"Do it. I certainly intend to." Sherlock smirked up at John for a moment, taking advantage of the momentary freedom to speak, then pressed an open-mouthed kiss on the head of his cock and included a particularly delightful little tongue waggle. His thighs tightened around John's leg, too, as his hips sped up and stuttered-

It took a whopping ten more seconds until that sinful mouth tipped everything over the edge. John let his head fall back and his own mouth drop open as he stopped trying to hold back - Sherlock certainly seemed to be doing fine, anyway, if the muffled noises of surprise and approval were any indication. John regained the ability to actually control his vision just in time to get a good eyeful of Sherlock seizing up and twitching as he came. Which he did as elegantly as everything else, his long neck arched and curls sex-tousled and his mouth open on a desperate gasp. John couldn't resist cupping his palm over Sherlock's cheek. Sherlock closed his eyes and leaned in against him, totally boneless and smiling like some post-coital Madonna.

"Knew that'd be 'mazing," Sherlock slurred without looking up.

"You've had more time to think about it, I suppose."

Sherlock hmmed, a little contented sigh. "Lots." He sat back on his heels, releasing the hold his thighs had claimed on John's leg, and made no move toward cleaning himself up. Or even any acknowledgment that his now-softening cock was right there in his lap, sticky with his own come, and that said come was also smeared all over John's trousers. "Are you having second thoughts?"

John actually considered that for a minute, but . . . "No, I don't think so."

"Not going to worry about catching gay cooties?"

Berk. "I'm not actually as stupid as you seem to think I am sometimes."

"I don't think you're stupid." Sherlock frowned. "I wouldn't have instigated this if I'd thought there was any significant chance you'd let it ruin our . . ."

"Friendship?"

Sherlock inclined his head. "I'm still not used to that term."

"So deal with it." John was still feeling a bit floaty and euphoric, but some things transcended all that. Such as the need to reassure Sherlock that he was, indeed, important to someone. John, in particular. "Might I suggest a new term?"

"I don't do pet names," Sherlock said primly.

"God, no. I was going to say 'friends with benefits.' Seems apt. Since neither of us are the 'boyfriend' type."

"Mmm." Sherlock bit his lip, looking thoughtful, for several seconds. "Tell me . . . would these 'benefits' involve orgasms?"

"Didn't I just tell you I'm not stupid?" John reached down to grab Sherlock under the armpits and tug until the lanky detective was more or less sprawled across his lap. Which was surprisingly comfortable, actually. "I'll be honest with you, Sherlock - I don't think I'm ever going to be interested in full-on gay sex. The whole concept kind of grosses me out, actually. That doesn't mean I wouldn't be happy to do some experimenting with you, though."

Sherlock brightened at the word experiment. "I - I think I'd like that."

"Give me a few days to think it through, yeah? I honestly don't know what all I'll be up for, but you can keep notes for me if you want."

"I . . ." Sherlock was positively beaming. "John - yes."

It wasn't the girlfriend John had always envisioned for himself, but it would do. Perfectly.