Password Protected

A/N: Because, really, every fandom needs a good Harry Potter AU. This fanfic is partially inspired by dauntingfire's fanart of Sherlock and John in Hogwarts' uniforms which can be found here: ht*tp:/*dauntingfire.*deviantart.*com/*#/*d36zx50 (remove all *).

John Watson climbed tiredly through the portrait-hole, letting his book bag drop from his sore fingers onto the floor of the Gryffindor common room. He yanked testily at his red and gold tie to loosen it, his eyes drifting around the quiet room until they fell on the only other student present: a skinny boy with messy dark curls sat in one of the armchairs near the fireplace, his long thin fingers steepled in front of his face as he stared into the flames, apparently lost in thought. The unmistakable green of his uniform proclaimed him a Slytherin. His distinctive prominent cheekbones proclaimed him Sherlock Holmes, undeniably the most brilliant student to ever be sorted outside Ravenclaw House, and arguably far more brilliant than any who had been sorted into Ravenclaw as well.

"How-how did you get in here?" John spluttered, staring at the other boy in disbelief.

Sherlock's gaze flicked to John momentarily, then back to the fire. "Through the portrait-hole."

"It's password protected!"

Sherlock's voice was filled with disdain. "After a fashion. Your 'password' took me less than a minute to guess. It's not exactly Gringotts."

John trudged over and flopped down in another chair facing the fire. "This isn't the first common room you've broken into."

"Hardly." Sherlock smirked slightly. "I visit Ravenclaw Tower at least once a day." He rolled his eyes. "Really, that whole 'riddle' nonsense is nothing more than a taunt begging someone with real wits to break in. They really should have someone at least half-ways clever come up with these 'riddles,' though; the last twenty-two have been so simple, even you could guess them, probably on your first try." John glared at Sherlock, but Sherlock ignored him. "The biggest challenge is, of course, the moving staircases, but once you figure out the pattern, it's all quite simple."

John's eyes widened in shock. "There's a pattern to the moving staircases?"

Sherlock favoured him with a disdainful glare over the top of his steepled fingers. "Of course there is."

"And may I ask how long it took you to figure the pattern out?"

"Well, it did require considerable time, because the pattern itself only repeats every twenty-two hours, but of course, I didn't have to actually observe it for an entire cycle in order to deduce the pattern in its entirety—in fact, anyone attempting to do so would very likely come to a premature and extremely erroneous conclusion, because there are several clever points in the pattern designed to appear to be repeating patterns, but of course they only repeat two or at most three times before the pattern appears to change once more—all of this I can only assume was specifically designed to have the appearance of true randomness, but anyone who understands even the most basic principles of how magic actually works would know this to be impossible—"

John smiled pleasantly, leaning forward in his seat. "This is all really and truly fantastic, Sherlock, amazing really, but...how long?"

Sherlock narrowed his eyes at him. "A total of thirty-nine minutes."

"A total?"

"Over the space of five days," Sherlock admitted reluctantly. "But it's not as though the 'teachers' and 'prefects' of this supposed 'school' actually allow anyone to spend reasonable amounts of time studying anything interesting; if they catch a student watching the staircases move when he's 'supposed to be in class,' they physically drag him there and then have all sorts of supposedly secret meetings about him where they discuss how 'worried' they all are that he's not 'applying' himself and spend the better part of an hour bickering amongst themselves over the all-important question of whether he's just incredibly lazy or if he's really just a great dullard—which is entirely contrary to the overwhelming evidence that he is, in fact, far more brilliant than any of the people at this meeting, especially given the fact that not a one realizes the student in question is in fact witness to the entire proceeding, despite the 'security precautions' they took to keep the meeting 'private'."

John shook his head. "You listened in on a meeting the teachers were having about you?"

"Of course I did."

John sighed. "They're wrong. You are more brilliant than any of them."

"Of course I am." Sherlock smiled slightly at John. "It's still nice to hear someone else say it now and again."

John's answering smile turned to a small worried frown. "Aren't you worried you'll get caught in here by a prefect?"

Sherlock smiled a small smile and mischief flashed in his eyes, as he gazed once more into the fireplace. "Both of your Gryffindor prefects will be otherwise occupied for at least the next thirteen minutes."

John frowned slightly and was about to ask how Sherlock could possibly know that when Sherlock explained: "The two of them are currently both inside the same broom cupboard at the end of the fifth floor corridor."

John laughed in embarrassment. "I..I didn't know."

"Really, John, they're in your house. I'm not sure how you could miss the obvious signs."

"Obvious signs?"

"Like the way she turns down the tops of her socks."

John rolled his eyes. He decided he really didn't care what socks had to do with anything. "So can I expect this to be a regular occurrence?"

Sherlock raised an eyebrow at him.

"You showing up in my common room, I mean," John explained.

"Most definitely," Sherlock replied. "It's far more conductive to thinking than that dungeon in which I'm supposed to spend my free time. I especially like the fireplace." Sherlock looked momentarily thoughtful. "This fireplace, which of course you know, happens to be on the floo network. It really is a wonder that no one seems to use that as a convenient way to get in and out—what's the point of a password, when anyone with a bit of floo powder could simply bypass the portrait-hole altogether?"

"I-I'd never thought of that."

Sherlock smiled smugly. "Of course you didn't."

A/N: I'm actually Canadian, so it's entirely possible that I didn't make these British characters attending a British school speak entirely believably and British-ly as they should. If you're British yourself and you notice something wrong with the way I have these characters speak, please let me know; I like things to be all accurate and stuff.