For the first time in pretty much forever, Sherlock was the one to bring in the mail. This was the main reason John didn't see the hand-addressed envelope until it was too late and Sherlock had the contents spread out across the desk.

"What's that? Case?" John asked when he noticed Sherlock poring over several sheets of paper.

"Mmm. No." Sherlock looked up at him, eyes narrowing, then back down at the papers. "Sent by a friend of yours from uni, I'm assuming. You've changed less than I would have thought."

John felt a sudden wave of dread sweep through him. Surely it wasn't-

"Oh, there's a note. Excellent." Sherlock scanned the half-sized paper quickly, then sat back and smiled his I'm-truly-enjoying-this smile. "Ah, not a friend, just an acquaintance. But a fan of your blog, and who applauds us for our courage in being so public about our relationship despite the current political climate. Rather sweet, actually. You've inspired him to come out to his family, finally, after twenty years. Although really, I don't know how they wouldn't have already noticed. His handwriting is a dead giveaway."

John reflexively got as far as "I'm not-" before catching himself and taking a deep breath. There was no point in arguing with Sherlock - they'd been over this a hundred times before. Sherlock didn't see the big deal in allowing people to assume they were a couple, because that assumption was stupid and only stupid people would believe it despite all the "obvious" evidence they weren't shagging. John's assertion that Mrs. Hudson, Harry, half the Yard, and apparently even Mycroft believed there was something between them still couldn't change Sherlock's assessment. (He rather suspected it was because Sherlock classified everyone in the world except himself as "stupid" and thus not worth bothering over.)

That left the contents of the letter, though. John wandered close enough to look over Sherlock's shoulder. And shit, yes, the drawings were exactly what he thought they would be.

And Sherlock was back to being engrossed, lifting up first one page and then another, hunching over to scrutinize the lines, occasionally glancing up at John's face or chest or arm before refocusing on the drawings. "You've gained a good two stone," he said absently.

John cleared his throat. "Sherlock-"

"No need to be embarrassed," Sherlock said matter-of-factly. "Art modeling was a solid choice - I assume the pay was good, it took a limited amount of time away from your studies, and you didn't normally socialize much with art students so the social discomfort would have been minimized. You don't regret it, do you?"

"I didn't, until someone mailed you a bunch of nude drawings of me from twenty years ago and you started giving me that look." Sherlock tried to fake a contrite expression, and John glared. "Yes, that one. The one you were doing just a moment ago."

"I'm just curious-"

"You're always curious, Sherlock. And you have no sense of when you should shut it off. That's why we've got a singed spot on our kitchen ceiling and why the receptionist at the morgue isn't speaking to you and why Anderson follows you around at crime scenes reminding you to not touch anything. Go be curious at someone else."

Sherlock's frown deepened. "I'm not trying to treat this like an experiment, I promise. I just - it's an excellent opportunity to compare."

"Compare," John repeated blankly.

"You. Then and now. What changes in musculature the human body goes through as it ages." He suddenly brightened. "Oh, John - take off your shirt."

"What? No."

"Please?" Sherlock jumped up out of his chair and headed for his bedroom. "I've got a decent camera in here somewhere - I can take pictures now and then I won't have to bother you again."

"No." John crossed his arms. "How many more times do I have to say it? Absolutely not."

"Why not?" Sherlock turned, genuine confusion on his face. "I said please, I was polite, and I'm trying to be considerate of your time. Did I miss something?"

Posh, arrogant git. "You missed the part where I'd have to be okay with you taking semi-nude pictures of me."

Sherlock waved lazily. "Not semi-nude - I want to chronicle the whole thing. Please."

"Just - no. No way in hell am I allowing that. I don't even send those kinds of pictures back and forth with girlfriends."

Sherlock stared at the ceiling for a moment and tapped his fingers on his leg in a random rhythm, then re-focused his gaze on John's face. "What if I draw you? Would that be all right?"

That . . . pretty effectively derailed John's indignation. He cocked an eyebrow. "You can draw?"

"Of course."

"I don't believe you."

"Come look, then." Sherlock swept through his bedroom door, leaving it open in a clear invitation for John to follow. Which he did, albeit with a strong sense of impending doom.

Sherlock rummaged through his closet, digging in boxes, until-

"Aha. Here." He extracted a somewhat yellowed sketchbook and pressed it into John's hands. "I may be a bit out of practice, but Mycroft and I did have an art tutor for several years. I didn't stick with it, but you should see Mycroft's watercolors."

John flipped to somewhere in the middle - and stopped. It really was just a simple sketch, a few dozen lines at most. A much younger Mycroft, a bit thinner and with a hint of a smile, relaxing in an armchair and reading a book. The chair was just an impression, a few broad swipes of the pencil to give perspective, but the accuracy of the detail on Mycroft himself was absolutely stunning. The perspective was from an odd angle and at a distance, like Sherlock was peeping in through a doorway and furtively sketching while Mycroft wasn't watching. And even though John had never seen a picture of Mycroft at this age, might not even have been able to pick him out of a crowd in a photo, the drawing absolutely captured the arrogance and the self-control and the fierce refinement of the man, all in a few lines. It was amazing.

He flipped to another page. This one was a mishmash of random faces - some old, some young, both men and women, from all different angles. Along the bottom was a stunningly detailed sketch of a Tube station, people pouring out of the car as it stopped. Upon closer inspection, John noticed that each individual face sketched on the top of the page appeared somewhere in the larger scene at the bottom.

"You don't draw anymore?" he asked absently, flipping through more pages.

Sherlock leaned against the wall and shrugged. "I do in my notes, when I need to record bacteria or leaf formations or the like. When words aren't sufficient. But no, I haven't drawn people in years."

"Why not?"

He shrugged again. "Never wanted to."

John closed the sketchbook and handed it back. "But now you want to draw me."

". . . Yes."

"Nude."

". . . Yes." Sherlock's tongue darted out to moisten his lips, a tiny tell that he wasn't as indifferent to John's response as he wanted John to believe. "If it makes you uncomfortable, I can just draw your face, but I'd rather get the whole picture. Since the other drawings are available for comparison." He paused, flicked his gaze to John's eyes and then away. "What if I promise not to make any more messes in the kitchen for the next week?"

John couldn't help it - he laughed. Bloody hell, my life is strange. He lived with a flatmate who solved murders, who left human kidneys boiling on the stove and forgot to mention it when John went to cook spaghetti, who thought basic flatmate courtesy and things like not setting fire to the kitchen table were bargaining chips to be used in negotiations. And who thought asking his straight flatmate to strip and pose nude - for science, of course - was a perfectly reasonable thing to do.

Fine. John took a deep breath and nodded. "Okay. But."

Sherlock blinked. "But?"

"But one more thing. Two, actually." John folded his arms again. "One is that you're going to make an honest effort not to piss me off for the next week, including not trashing the kitchen."

Sherlock nodded. "And?"

"And someday you'll explain to me why I'm absolute crap at saying no to you."

The grin nearly split Sherlock's face. He said nothing, though, just grabbed a pencil case from somewhere in the box and clutched the sketchbook to his chest and nodded toward the door. John led the way back into the living room.