John Watson has patched Sherlock Holmes up, nursed him back to health, and has dealt with the fallout of his flat mate wandering naked and yawning into the lounge after a fourteen hour nap while John and a date are watching telly. John knows most of the lines and contours of Sherlock's body, if not every scar and freckle.
But it all looks different when you're sitting at the kitchen table, watching your flat mate stand naked at the counter scowling at the tea kettle the morning after he's had your dick in his mouth for the first time.
The first time? Implying there would be more times. Let's not think about that. Instead, he looks at Sherlock, who may be running calculations pertaining to the exact moment the kettle will boil, or he could be lost in his mind, cataloguing the events of the previous night, or deleting them, or thinking about some other matter entirely.
He tries an exercise that Sherlock has encouraged him to do to practice his deduction skills.
"Do it backwards," he'd said. "Take the things you know about a person and look for the patterns and markers those things leave."
John stares at his friend, and decides he must be lost in his Mind Palace. Normally such intense scrutiny from John would result in a defensive "Problem?" from Sherlock. He usually only stares at Sherlock when he's said something appalling.
Sherlock doesn't register John's gaze, or that the kettle has boiled.
Right. John knows that Sherlock has just awoken. How would he know if he didn't know?
Hair in disarray, more flattened on the left side. Creases from pillowcase wrinkles on left cheek. (New data: side sleeper, favors left side. )
John knows that Sherlock has engaged in some form of sexual activity recently. How would he know if he didn't know?
Love bite on right side of neck, and on left shoulder, and on left pectoral, and on right hip. Smallish bit of dried semen in his hair above his left ear. Also indicative that Sherlock Holmes does not swallow, and that in fact, he will not accept ejaculate into his mouth at all.
John knows that Sherlock has not had significant case for a week and a half. How would he know if he didn't know?
Chemical stains on fingers meaning more time to work on chemistry experiments as well as less time dealing with the public and having to maintain a neat appearance. Only the third and fourth ribs are visible on his slight frame, as he eats more regularly when he isn't on a case. Body more toned overall due to killing time with swimming, fencing and boxing. Abdomen not anything close to rounded but not concave.
John knows that Sherlock Holmes gives a magnificent blowjob. How would he know if he didn't know?
And here he stops. Because, beyond the kind of lips John's mates used to call DSLs (Dick Sucking Lips) there is really little about Sherlock Holmes that would make one think he had any awareness that penises existed beyond his own, much less that he rivaled a Dyson in terms suction and efficiency.
Something John doesn't know but thinks he's deduced is that last night wasn't Sherlock's first time doing that. He initiated a lot of girls into the world of fellatio as a young man, and it had never been like that, especially without instruction. He opens his mouth to ask him where he learned, but stops.
"At school, of course. Don't be dense," Sherlock says. He pours water into the two waiting mugs and goes to the refrigerator for milk. He makes an exasperated noise, slams the refrigerator door and stalks into his bedroom. Two minutes later he comes out wearing pyjama bottoms and a t-shirt and flops face down on the sofa.
"No tea, then?"
"No milk."
John gets up to retrieve his mug before the tea over steeps. He doesn't mind going without milk, though it sometimes reminds him of the leaner days of his childhood.
"It's your turn to go get it," John says, settling into his armchair.
"It was my turn last time," Sherlock says into the couch cushion.
"Yes, and I went and got it."
Sherlock's response is completely lost to the couch cushion.
"What was that?"
Sherlock turns over. "I said that it's the least you could do to return last night's favor."
John laughs, a deep belly laugh that dispels some of the tension, but stops abruptly when he sees Sherlock's face.
"Sherlock, it really doesn't work that way."
"Doesn't it?" he asks, looking John in the eye for the first time that morning. Sincere.
John stands up and crosses to the sofa. He looks down at Sherlock for a moment, noting how his eyes widen as his lips part. He considers he best approach for a moment before he straddles his best friend's hips and leans over him, hands fisting in his t shirt.
"It doesn't. And if for whatever reason you've decided to explore this part of yourself for the first time or again or whatever, whether it's with me or someone else, you need to remember that."
Sherlock nods, slowly, and John's hands relax, releasing Sherlock's shirt. John smooths the fabric over his friend's chest and sits back.
"Right. Now that's sorted, you'd best get some shoes on before you go to the shops."