Two weeks after they solved the case and a week after John'd made Sherlock read (and watch) the entire Harry Potter series because the man had started all but literally climbing the walls with boredom, one day out of nowhere, Sherlock lifted his head up from dangling off the couch as he read something in what looked like Latin and proclaimed, "Ravenclaw."

"I'm sorry, what?"

"Ravenclaw. I am clearly a Ravenclaw."

John chuckled, folding the paper he was reading. "I'd have guessed Slytherin."

"Dull. And Mycroft is Slytherin. He's a slimy fat git who wants to run the world and likes starting wars."

"...OK, yeah, he's Slytherin," John said, not able to fault that logic. "And I'm Hufflepuff, then, am I?"

Sherlock gave him the look he only gave John when John did something he considered especially stupid. "Hardly. That's Lestrade's house. Sally's a Muggle and Anderson is a definitely a Squib."

"So where am I?" he asked, genuinely curious - he'd have laid five quid on him getting Hufflepuff, if he'd have bet money at all on Sherlock doing an impromptu Sorting of all things.

Sherlock made an annoyed noise. "Gryffindor, of course. You with your taste for danger. Stop being so thick," he said. "That's why you're not in Ravenclaw," and went back to dangling his head off the side of the couch.

Well. Yeah, Harry Potter was a win, then, John thought, and couldn't help the grin. "A taste for danger, eh? Pretty sure you're in Gryffindor with me, then," he said, and the corner of Sherlock's lip went up.

"Possibly," he said. "...Probably."

"Definitely," John corrected. "Hermione was in Gryffindor, don't forget, and she was more clever than anyone, too. No Ravenclaw is going to go jumping over fences and playing guessing games with serial killers. That's a Gryffindor through and through. Now, tell me what you changed my password to or I'm tossing your nicotine patches and your cigarette stash. And telling Mycroft you're bored and need something to do."

"I take it back. You're Slytherin."

"Too late. Already Sorted," John said, then tried "Gryff1nd0r" just to see. "And never mind, got the password, thank you. A bit obvious, that."

"Ten points to Gryffindor," came a low chuckle, then Sherlock went back to his book, tapping a finger against the book in what sounded an awful lot to John like the drum beat to "Rumour Has It".

John started typing up his blog, but decided this whole conversation was, like a lot of things that happened in the flat, not for sharing.

And he didn't even notice he'd started humming the two note introduction to "Rumour Had It" in time with Sherlock's tapping. Not until Sherlock piped in humming the melody, and yeah - that one wasn't for the blog.

—

And as he suspected, the next crime scene, Sherlock did indeed pick up a stick, point it at Anderson, and yell, "Oh, Avada Kadavra!" at him.

It didn't work, but John'd be damned if the look on everyone's faces hadn't been worth it.

Also worth it was the look on their faces when John, without missing a beat, said, "Unforgivables are a bit not good, Sherlock."

Sherlock looked over his shoulder. "Even on Anderson?"

"Even on Anderson."

He sighed dramatically as he tossed the stick, then turned back to the body.

"The two of you are fucking mental," Sally burst out with, just as Anderson yelped, "HE reads Harry Potter?!", so John added, "And especially not good in front of Muggles," to Sherlock before he smiled at Donovan.

John couldn't see it for certain because his back was to him, but he was pretty sure Sherlock was smiling, too.

There were reasons, after all, for why they got on.