"Bored."

John gritted his teeth, trying not to snap at Sherlock. The other boy had been repeating the same word at three-minute intervals for the last half an hour, while simultaneously blowing holes in the hangings over John's bed. It had taken Sherlock four days to break into the Gryffindor common room, but John got the feeling that it was only because the other boy had been trying not to. He didn't imagine the password was actually much of a challenge.

All John knew for sure was that two weeks ago, Sherlock had suddenly appeared in front of the chair he was sitting in and announced that he was doing an experiment and needed John's help. He'd agreed, if only to get Sherlock out of the tower and stop the rest of his house from glaring at them, but Sherlock seemed to have taken the fact that John hadn't yelled at him or told him explicitly to get out as some sort of unspoken agreement between them that Sherlock could poke his nose into John's business whenever he felt like it.

Now Sherlock spent as much time in John's dorm as he did in his own, maybe more, and while most of the other Gryffindors didn't like it, they also didn't say anything anymore, so long as it was obvious that the Slytherin was only passing through their common room to find John and had no intention of actually staying there.

Sherlock had transfigured John's slightly battered trunk into a slightly-more-battered desk, with lots of drawers that fit all of his clothes and things even though he didn't think they should. Then he'd helped John lug one of the smaller, less comfortable chairs, the one least likely to be missed, out of the common room and up the stairs. Sherlock was fully aware that John's dorm room was somewhat less off-limits than the common room, though he didn't really seem to grasp that it was because that way the rest of the Gryffindors could pretend he wasn't there.

John supposed he was just lucky that Sherlock had deigned to set him up a place at all rather than just taking over the bed and leaving John to sit on the floor. He didn't much feel like adding "Budge over, it's my bed anyway," to the list of arguments they had all the time, not when he spent so much time already saying things like, "Really, Sherlock, you've got to eat something," and "No, I won't do your homework for you, you're perfectly capable of doing it yourself," and "I don't care if you can make it look like an accident, you still can't blow up Anderson." Part of being friends with Sherlock was keeping him on track and not putting up with his crap, but at some point enough was enough. John had to pick his battles, and it was nice to have one less thing to fight about.

Now John was sitting in the chair, at the desk, working away while Sherlock sprawled across his bed like he owned it, blew holes in the furniture and kept the rest of the first-year Gryffindors John shared the room with away from them, just by existing. John wasn't quite sure why he put up with it. Maybe it was because he knew Sherlock didn't have anyone else. Maybe it was because the other boy was so exciting and fun when he wasn't being frustrating like this that it balanced out. Maybe it was because he knew trying to stop Sherlock doing whatever he wanted was going to be futile anyway, even if he was better at corralling his best friend than anyone else seemed to be. He sighed.

With a bang, Sherlock blasted another hole in the curtain over the bed. "Bored."

This time, John couldn't stop the words before they came out. "You know, you could work on our Potions homework like you're supposed to."

Sherlock rolled over onto his side to stare at John for a moment. "And that's supposed to make me less bored, John? I could do it in my sleep!"

John rolled his eyes. "And yet somehow, you never do. . . Anyway, it can't be any worse than just lying there."

Sherlock looked thoughtful, then rolled the rest of the way over so that he was right-side-up. "You're right. We've got to get out of here. Just let me think for a minute." John groaned. Whatever Sherlock came up with was likely to take hours and leave him to finish his homework in the middle of the night, while everyone else was asleep, like he'd been doing for basically the entire time they'd been at school. At some point, he should probably put his foot down. Except he didn't actually want to do his homework any more than Sherlock did, so as soon as the opportunity to go off on his friend's latest wild goose chase appeared, he was sure he would jump at it.

He sighed again and wrote faster, trying to copy out the rest of the passage on dittany before Sherlock dragged him away in the middle of a question. That was always the worst, because he'd spend half of their adventure thinking about the things he'd left half-finished, but when he got back he'd have lost his train of thought anyway. Just as John was dotting his last "i", Sherlock sat bolt upright, as if he'd been electrocuted. "Of course! How could I not think of it earlier?"

John sighed, putting his quill down and capping his bottle of ink. "Think of what?"

Sherlock leapt off of John's bed and grabbed him by the wrist, dragging him along toward the doorway. "Come on! We're going to do something no one's ever been able to do before!"

John trailed along behind Sherlock, hurrying to keep up as the taller boy half-leapt down the stairs into the common room. He was beginning to get used to the feeling of his friend's wiry fingers wrapped around his wrist and dragging him along. But at least they weren't actually holding hands. That could get a bit embarrassing, and Sherlock was sure not to notice the awkwardness. He seemed immune to what other people thought about him, which John sometimes hated and sometimes just envied. "What's that?" John asked.

Sherlock glanced around them at the people in the common room, who were glaring in their general direction as usual, made a face at Sally, who he had come to hate almost as much as he did Anderson, and answered, "You'll see."

Once they were outside, Sherlock kept going, dragging John along without a word, and John put up with it even though the things Sherlock was most tight-lipped about were almost always the most dangerous, frustrating, messy, and ridiculous. Or maybe he put up with it because the things Sherlock was most tight-lipped about were almost always the most dangerous, frustrating, messy, and ridiculous. They were also, inevitably, the most fun.

Sherlock didn't slow down until they were all the way outside, looking around for a moment – just long enough for John to extricate his wrist from Sherlock's viselike grip – and taking off again, almost sprinting across the grounds with John barely keeping up beside him. Then he stopped abruptly in front of a tree, which sat in the middle of a small clearing of its own.

John wasn't ready for the halt and kept running, only to find that the tree attacked anyone who came under its branches. Just as he was about to be flattened by a particularly large branch, Sherlock grabbed the back of his robes and pulled him out of the way. "Don't get too close," he said calmly. "This is a Whomping Willow."

John couldn't help glaring a little. "You could have warned me, you know."

Sherlock looked not-quite-ashamed. "Maybe. I was excited."

It was as much of an apology as John was likely to get. He sighed, and moved on. "Ok, so why are you excited?"

Sherlock looked at him, puzzled. "Well, isn't it obvious? There's something under it. It's guarding something."

John rolled his eyes. Obvious. Right. "And this meant we had to run because?"

Sherlock turned toward John and grinned, a slightly insane glint to his eyes. "Because I don't know what it is."

John raised an eyebrow. "You can't even guess?"

Sherlock grinned. "I can't even guess. Not enough data. Isn't that exciting! I love a mystery. . ." He started walking around the tree in a circle, staying carefully outside the reach of its branches. "But how do we get under it?"

John glanced back at the castle. Now that this had turned out to be less immediately exciting than it might have been, he wished that he'd had time to bring his homework with him. For some reason, Sherlock insisted that John stay near him when he was thinking, even if that meant John had to watch him walking in circles for hours. If John left anyway, which he did sometimes when something seemed important enough, Sherlock was sure to go all pouty and boring for the rest of the day.

Maybe he could find some kind of spell that would materialize his homework in front of him wherever he was. Maybe it was depressing that he was daydreaming about homework-materializing spells. It seemed a little pathetic. Maybe he'd better focus on the matter at hand and worry about his homework later.

John started walking around the tree, too, in the opposite direction from Sherlock so that they passed each other once on each side. Sherlock said nothing, staring at the branches like they were jigsaw pieces he was trying to put together. After a few minutes, he started running under the branches and then back out again, as if trying to gauge the tree's reaction time. John had already almost been hit by one of the branches and he stayed well out of its reach, staring at the trunk as he got more comfortable with the size of his circle. Then he noticed it – a small hole at the base of the trunk, like the entrance to a tunnel.

"Sherlock, come look at this!" Sherlock ran across the space under the tree's branches, dodging two and diving under another in a surprisingly nimble roll before John pulled him out of the way of the last branch, which Sherlock glared at suspiciously as though he hadn't been expecting it.

"What am I looking at, John?" he asked, still watching the branches as they flailed toward the boys like they thought trying harder might let them reach far enough to hit them.

"The hole at the base of the trunk – I think it's a tunnel. You were right. There's something under there."

Sherlock was beside himself, grinning like an idiot as he stepped forward for a closer look so that John had to pull him back again, glad that his friend was rail-thin and not overly difficult to haul around by the back of his robes. "Obvious!" Sherlock exclaimed, looking ashamed of himself for the first time John could remember, and calm enough that John decided he could let go of his robes.

"Sorry, John, I should have looked there first." He went back to studying the tree for a moment. "I think I can get to it." Before John could stop him, Sherlock darted forward, dodging the branches like he knew where they were going to come from before they got there – until one of them hit him across the right shoulder and sent him sprawling.

John was moving before his brain could catch up to his body, mimicking most of Sherlock's movements as he tried to get to his friend. Then he realized what he was doing, forgot what Sherlock had done, and moved on instinct, ducking, dodging, and rolling and getting no closer to his friend as he tried not to get hit. Luckily, he'd always been good at dodgeball.

He glanced toward Sherlock, who had managed to drag himself toward the trunk a little, but got distracted enough in that brief glance to miss a tree branch headed for him. It hit the side of his head with what felt like the force of a train and then he was on the ground, trying to roll out of the way of branches his eyes didn't seem to want to focus on. He got hit in the side next, hard enough that it started to be hard to breathe and hard to see, and when the branches suddenly stopped, he was too relieved to wonder why.

"John, get over here!" Sherlock hissed, "It's a long tunnel! Whatever it's hiding is big!" John tried to stand, but he couldn't seem to find his balance, so he crawled toward Sherlock instead, feeling like he was moving too slowly. The branches started moving again and Sherlock hit a knot on the side of the tree, stopping them again. So that was how it was done. John felt a moment of vague appreciation for Sherlock before the throbbing in his head erased it again.

Sherlock was looking at John as though he were a puzzle, now, like he'd been looking at the tree before. "Come on, let's get down into the tunnel," he said, but his words and his thoughts were clearly not the same. John had learned to recognize when Sherlock was thinking one thing and talking about something else, because it was a good hint that there was trouble coming. John nodded, then followed Sherlock as the taller boy crawled down into the hole. He thought if he hadn't been hit in the head, he would probably be having an easier time of the whole crawling thing, but as it was, he kept bumping into the walls, wishing Sherlock would slow down a bit and make it easier to keep up.

At the end of the tunnel, they came out into a tiny, filthy room full of furniture in even worse shape than John's desk. There were claw marks in the walls and the furniture, chairs with legs missing, tables with gouges across their tops – it wasn't anything as exciting as they'd hoped. Or, at least, as John had hoped. Sherlock was looking around them like it was a marvel.

John sat down on the floor, head still ringing too much to stand, watching his friend dash back and forth across the room, looking at it from every possible angle. Then Sherlock's eyes met John's for a moment and he stopped running. "Oh! Sorry, John, I forgot." Sherlock muttered something John couldn't quite hear, and a jet of blue light shot out of his wand, hitting John in the head and clearing up his vision in an instant, the throbbing disappearing as his eyes started to focus again.

John stood up cautiously, testing out his balance. "Thanks. What was that spell?"

Sherlock waved a hand dismissively. "Fixes concussions. Should have remembered earlier. You might want to go see Madame Pomfrey when we get back anyway. 'S been a while since I did that one."

John wasn't sure why Sherlock knew an anti-concussion spell or what he'd have been using it for before now, but he didn't ask, because Sherlock had clearly stopped paying any attention to him at all, racing across the room one more time and then vanishing out the door to check out the next room over. John followed him, still moving tentatively, because while he certainly felt like Sherlock had fixed him, he couldn't quite get past the feeling that he hadn't been able to trust his own body.

Sherlock looked like a kid in a candy shop, racing around and poking at things and banging on the walls and trying to solve the mystery. John could tell by looking around that whatever this place was, the explanation was sure to be another of those things that Sherlock called "obvious" but that was not obvious at all to a kid who had grown up muggle and still knew basically nothing about being a wizard. Instead of trying to solve the mystery, he just took in their surroundings.

Now that he'd gotten over the disappointment of it not being something big and grand and shining, it was actually pretty cool down here. It was like he and his friends had wanted their no-girls-allowed treehouse clubhouse to be when they were eight – all manly, solid furniture (or once-solid, at any rate) and no frills. Of course, when they were eight, they'd had to give it up because they had no furniture at all and what they could get away with filching from their houses was mostly frilly and girly and ridiculous, and besides that too heavy to haul into the tree.

Sherlock stopped his running after a moment, standing stock still in the middle of the room with his hands steepled together and his eyes closed, as if he were thinking very hard. Then his eyes snapped open and his face split into a broad grin. "Of course. Do you know where we are, John?"

John rolled his eyes. "Some secret run-down shack."

Sherlock whirled around dramatically, robes floating around him in a circle, and made a beeline for one of the windows. "Exactly. Or, more exactly, we're in the Shrieking Shack. Come look out the crack between the boards on the outside of this window." John followed him and looked where he'd been told to look, expecting the view to be some new angle of Hogwarts that Sherlock had used to figure out where on the grounds they were. Instead, he saw an unfamiliar town stretched out below them. It was small but looked pleasant, and he had no idea how they'd gotten here.

"That's not Hogwarts," he said vaguely. He didn't have to look at Sherlock to know that his best friend was rolling his eyes.

"'Course not. The Shrieking Shack's in Hogsmeade. Everybody knows that."

John rolled his own eyes. "Everyone in your world maybe. I've never heard of it."

Sherlock gave him that look again, like he was a puzzle that needed working out. "Right," he said vaguely, "Muggle. Well anyway. That's Hogsmeade, wizarding town right outside of Hogwarts. This," he turned around to gesture at the room they were standing in, "is the Shrieking Shack. 'Most haunted building in Britain,' they call it, except apparently it isn't, which is why it took me so long to figure out where we were. And now we've got a much better way of sneaking out to the first Hogsmeade weekend than the one I was going to use, as soon as I figure out how to get in and out of the building without anyone knowing we were here."

John wasn't sure what any of that meant, really, but he did know his best friend well enough to realize that they were about to be spending rather a lot of time in here. Something in Sherlock's face had changed as he turned away from the window to talk to John, and now he was looking around the room with a new look in his eyes, still intense, but with less wrinkling in the middle of his forehead, like he was planning instead of puzzling.

Well, hanging out here suited John fine. It was better than having Sherlock in his room all the time with the other Gryffindors mad about it, and it looked like even a bored Sherlock couldn't do much damage to it that hadn't already been done, which was something that couldn't be said of the curtains over John's bed.

"Shall we start straightening up in here, then?" he asked with a sigh. Sherlock nodded, waving his wand to reattach the leg to the broken chair. Sherlock knew an awful lot of magic, and it all seemed to be completely unrelated to the stuff they were doing in class, about half of which Sherlock failed to bother with because it didn't seem useful.

John was beginning to think Sherlock was right as he started rearranging the remains of the furniture by hand. Maybe the stuff they were doing in class wasn't useful. But he was going to do it anyway, because it was still magic and it was still cool. And now he could do it in here, where he could practice without looking silly in front of anyone but Sherlock, who seemed to find him vaguely silly a lot of the time anyway. This was going to be good. It was also going to take them forever to tidy up, and there was a good chance his homework would have to wait for the dead of night yet again, but John wasn't sure he cared. They had a place of their own now, and that mostly made it worth it.