Sherlock was working up to a good proper rant when John walked in and spoiled it. Sherlock stopped, mid-sentence, and glared.

"Where were you? I've been talking to you for half an hour."

John sighed and let the door swing closed behind him. "I was out at Tesco, Sherlock, just like I told you an hour ago. You really do carry on conversations when I'm not here?"

"Not intentionally."

"Why don't you just talk to the skull?"

"Because it doesn't know anything about penises."

That got John's attention. "Sorry, what?"

"Penises, John. I was soliciting your opinion."

John blinked. "Generally in favor, I suppose? Why?"

Sherlock made an angry slashing motion with his hand. "No, not that. About my situation."

"Right then. Better start back at the beginning, now that I'm actually present. I think I need to hear the full explanation for this." John dropped his sack of groceries on one of the kitchen chairs - the table was too full of Sherlock's laboratory apparatus to hold anything more - and came back into the living room so he could at least get comfortable in his armchair while Sherlock ranted.

"The Woman - she's the beginning of this." Sherlock dropped heavily into his own chair. "You saw it - she drugged me and hit me with her riding crop."

John nodded patiently. "Yes, I do rather remember hauling you back here and putting you to bed. What's that got to do with whether I approve of penises?"

"Nothing - I meant your medical opinion." Sherlock's eyebrows drew together. "While I was lying there on the floor, I got an erection. An erection, John. I don't understand - I never bother with those." He shook his head as if the thought of actually getting hard was patently absurd. "I assumed it was a side effect of whatever she drugged me with, but it won't go away and I don't know what to do."

"Sherlock, when you say it won't go away . . ."

"Not continuous, obviously, but I haven't allowed myself an erection since I was a teenager and now I get one nearly every time she texts me. Which is fourteen times today already."

"Ah." John tried to keep his best "doctor face" on. "You said you don't allow them - do you not get erections at all, or you just don't follow through?"

Sherlock shrugged. "I rarely get them, and when I do I ignore them until they go away. I've gotten it to where it usually only takes a minute or two."

"Ah," John said again, and chose his next words carefully. "You do . . . know . . . why she keeps a riding crop around, right?"

Sherlock rolled his eyes. "Obviously."

"So you know that some people find that kind of thing sexually stimulating."

"Your point, John?"

John sighed. "My point is that you may be one of those people, Sherlock. It's not something you can just decide not to be aroused by - you've got a kink. Big deal - most people do."

"Only slightly over half, depending on how you define the word," Sherlock answered immediately. And then paused. "I never thought about it in any sort of personal sense," he admitted.

John rather thought there might be a lot Sherlock hadn't considered in a personal sense when it came to this particular topic, but most people were strangely sensitive when discussing sex and it was entirely possible Sherlock might feel the same. Not that he reacted normally to other things, but this freak-out was definitely on the odd side even for him.

"Sherlock - do you consider yourself asexual?"

Sherlock tilted his head and frowned. "I don't have enough data to determine that," he finally said.

"Fine. That's fine." John stood. "I can't believe I'm saying this, but - as your doctor - I'm going to recommend that you go watch some porn and analyze your own reaction. Take notes if you think it will help. There's probably nothing medically wrong with you - whatever drug Irene Adler gave you should be completely out of your system by now - but it would definitely be good to make sure everything is working normally. And since you really don't need me here for that, I'm going to go put the groceries away and throw together some dinner. I picked up some chicken salad and some croissants - you hungry enough to eat any?"

Sherlock ignored him, instead reaching for John's laptop. John heaved a sigh and headed back for the kitchen. The pleasant silence lasted less than five minutes before Sherlock was calling him back.

"What is it, Sherlock?"

"Where do I find porn?"

"Are you serious?"

Sherlock shrugged. "Searching online appears to be useless - all the sites with high placement in search rankings want me to pay some ridiculous amount just to look through their archives."

John sighed, leaned over Sherlock's shoulder, and typed in a web address from memory. "There you go - take your pick." The screen filled with dozens of thumbnails of porn videos, most with badly misspelled titles like "HOT MILF GAGGGING 4 CUM" or "DP SEXY ASIAN PUSSY XXX." It wasn't John's normal go-to site for browsing, but it did feature an impressive variety of videos, it was free, and it wouldn't give his laptop a virus.

"Which one should I click on?" Sherlock asked.

John rolled his eyes, then pointed at a relatively tame video he had seen before. "Start with that one. And I can't believe I'm giving you pointers on how to search for porn."

"I've always acknowledged you had a few skillsets I don't," Sherlock said absently. "This appears to be one of them."

"Yeah, thanks. Because I've always wanted to be the porn expert." John hesitated - part of him felt like he really ought to go up to his room, now, before this got any stranger. The other part of him was wildly curious to see Sherlock's reaction, especially given the recent revelations.

But so far, Sherlock's only reaction was to glare at the screen with one eyebrow raised. That particular video was rather short and to the point - just an enthusiastic blonde getting pounded into the mattress by her dark-haired partner. They were both fit, and if the blonde had rather improbably large breasts and lips, then oh well. Par for the course when it came to porn, really. Sherlock turned the volume up, filling the flat with an embarrassing combination of wet squelching sounds and breathy moans, then abruptly turned the sound off.

"What is this supposed to accomplish?"

John sucked in a breath, counted to three, and slowly released it again. "People watch porn because they get aroused from watching other people have sex, Sherlock. If this isn't working for you, find something else."

"But they're not having sex - they're acting."

John eyed the rather vigorous activity progressing silently on the screen. "I rather think they're doing both."

"No, the body language is all wrong." Sherlock tapped parts of the image with one long finger. "This woman isn't even aroused - her pupils aren't dilated and her skin isn't flushed, indicating her blood flow level is barely high enough to take into account the gymnastics she's doing with her legs. The man is clearly thinking about something else - someone else, most likely. Ah - see how he avoids looking at her breasts or her waist? He's gay. Why is he filming porn having intercourse with a woman when he's not interested in women, John?"

"I'm sure I have no idea." John licked his lips and tried to will his own arousal away - fake or not, the scene was definitely doing something for him. "There are hundreds and thousands of videos just on that one site, Sherlock - keep looking until you find one where they're not faking."

Sherlock looked dubious. "If you say so."

John rolled his eyes. "Look for something with a riding crop, if you want."