"Nose."

"What? No, John, I haven't…"

"Nose, Sherlock, right now, on the wall."

Lestrade simply stared. He'd spent a fair few years watching Sherlock belittle and insult, well, everyone around him. And despite his best efforts, he'd never had any impact on the man's sensibility about it. So to say that Lestrade watched with genuine astonishment as Sherlock Holmes huffed, twirled his coat defiantly and then stood, back to the crime scene, with his nose pressed against the wall would be an understatement of truly gargantuan proportion.

"This is completely beneath me," Sherlock told the wall.

"No, it's really, really not. You behave with these people, hard-working people Sherlock, like a petulant child. How else should I treat you, then?" John crossed his arms, and Lestrade had to turn his head to hide a smirk.

"You should treat me, John, with the respect due my genius. I'm right."

"And an arrogant arse," John said. Lestrade smirked again; he'd not seen such masterful control over petulance since he and his wife had divorced. "It doesn't matter how right or how brilliant you are, that doesn't give you the right to be demeaning to other people."

"So you admit that I was right, and Anderson was an idiot."

Lestrade winced. Sherlock's tone was so triumphant, so utterly smug in his correctness, and so clearly the wrong inflection to take. Sometimes Lestrade wondered how someone as brilliant as Sherlock could be so socially inept, but in watching this scene with John, he had hope that some day he might not have to wonder anymore.

"Of course you were right. You're entirely missing the point, Sherlock. I can't see how, it's so glaringly obvious. You'd think the world's only consulting detective would be able to fathom it."

Oh, John was good. Very good. It was a shame he didn't have children of his own. Maybe some day, when he was done bringing Sherlock up, they'd consider it.

"And what, do tell, have I missed, John?"

"Why are you here, Sherlock?" John looked at Lestrade, and although he wasn't completely certain what John's point was he understood he would be expected to back him up, should it be necessary.

"Because the Yard needs me, obviously."

"Yes, fine. And good on them for calling in help when they need it, and not letting their pride get in the way of helping people. But why are iyou/i here?"

Lestrade had expected an answer, some argument perhaps, but John apparently did not. He paused, but not really long enough to give Sherlock the chance to respond.

"It's not the money. Even with the deal Mycroft and Lestrade were able to work, it's hardly keeping us in the flat, is it? And it's not because you want to catch murderers, or keep people safe. That's why iLestrade/i helped you get here, but that's nothing to you. You're here, Sherlock, because without this you'd be home, in our flat, bored into a state of catatonia."

More silence from Sherlock. His nose wasn't, strictly speaking, still pressed against the wall. Instead his head had dropped and his forehead was now resting against it.

"You're here, because iyou need this/i. I know it, and so do they. So perhaps, as a suggestion, you might want to consider the following. Mycroft and Lestrade had to do a fair amount of convincing to get you registered as an official consultant to the Yard. I doubt it would take much, say a few complaints from the field staff, to stop your ever coming back to a crime scene. The next time you feel a pressing need to tell Anderson exactly how stupid he is, remember this: if they can't work with you, you can't work."

It was only a moment before the stooped shoulders were straightened and Sherlock turned to face John.

"Quite right, John. It's alarmingly short-sighted of me to alienate those people with whom I must work." Sherlock paused, and Lestrade thought briefly he might not be able to get through it. "I'll do well to remember it in future."

"Fine. See that you do." Sherlock nodded and glanced back to the body lying on the floor. "Go on then, impress me." John waited until Sherlock was once again absorbed in the scene before him to let his guard down and smile fondly.

Lestrade leaned against the door frame and smiled. John Watson would make a good man of Sherlock yet.