Title: Of Bugs and Treehouses (tentative title)
Characters/Pairings: young!Sherlock, John, Mycroft, Harriet. Others to come, probably
Genre: General
Ratings/Warnings: G, PG at the most?
Summary: Every summer, John Watson and his sister go to the Cotswolds. This summer, he meets a young Sherlock Holmes.
Disclaimer: I do not own the BBC adaptation of Sherlock, Nancy Drew, or the Hardy Boys.
Notes: This fic was inspired in full by sherlulz on tumblr who drew a picture of young!John and Sherlock in the forest.

Part I

Every summer, Mum would take me and Harry off to the Cotswolds to visit her sister in a cottage near the forests. We'd been doing this since Harry was a tot. She doesn't like it much now.

Harry's my sister. She's kinda tall but kinda plump, too, and she never plays with me. When we were littler, though, we'd play dragon and knight all the time. I was the dragon. She got the princess.

But now we're older. Harry's eleven and won't talk to me because I'm just her kid brother, which wasn't fair because I'm nine. Not a kid. She didn't want to go on the summer trip, and Mum had to frogmarch her into the car to get us going. Harry didn't talk to me or even look at me.

"Now remember, John, Harry," Mum lectured from up front. "Don't go too far into the forest."

"Yes, Mum," we chorused.

"You say that every year," grumbled Harry, pouting. I watched her cross her arms and skulk for a moment before pulling out a Nancy Drew book. I'd snuck some of Harry's books when she wasn't looking, and I didn't really see what she saw in Nancy – she was a bit too talented, I thought. Not that I didn't mind talented, really. Talent's okay. Nancy was just too perfect.

I preferred the Hardy Boys, anyway.

Aunt Petunia's cottage was old but familiar. She'd had it as long as I could remember, after all, so of course it had to be old. It was just down the road from a big old stone mansion that belonged to the Holmes family, but I'd never seen anyone in there. Actually, no. I had seen people in there, but just as lights and shadows. Nothing else. I'd always wondered if they had people our age. My age. I get so dreadfully bored nowadays because Harry ignores me.

Harry ran inside with her things as soon as we stopped. Mum and I greeted Aunt Petunia; she'd grown skinnier and older and a lot less happy-looking. I guess it's because Uncle Billy died a long time ago and she hadn't gotten over him. I had been two.

My old room in Aunt Petunia's cottage was just the way I'd left it, only with changed sheets. Aunt Petunia had dusted everything, though, because she had left her duster on my desk. I liked my desk; it had lots of drawers and a bright lamp for reading. From the window I could see the forest and a bit of the Holmes mansion. There were no lights.

I liked it in the Cotswolds, really. I must sound so sad about going here, but I'm not. Really. A whole summer running around through the forest and climbing trees was lots of fun! Harry killed some of it by not playing along, but I honestly loved Aunt Petunia's house and the big forest just beyond the backyard.

I looked out at the trees. This summer I was going to build a treehouse.

I didn't have a very good morning. On the way down I bumped my shoulder bad and fell down the stairs. Mum put a plaster on my left knee. It hurt. I had to limp into the kitchen. Harry snorted at me so I stuck my tongue out at her.

After breakfast – it was really good; Aunt Petunia makes the best bacon and eggs – I was going to go to the woods to find a good tree for my treehouse, but Mum pulled me aside. She looked serious about something and for a moment I wondered if I'd accidentally done something wrong like leave the seat up again.

"Be careful, Johnny," she whispered, patting my bandaged knee. "Aunty's told me that some bad things have been happening in the woods this year. People have disappeared."

"Disappeared?" I echoed.

"Yes, gone. Snatched. You better make sure you don't get lost, dear. Here." She handed me a compass with a smile on your face. "Uncle Billy's old compass. He'd want you to have it now that you're a big boy."

"Thanks, Mum," I replied, smiling and trying to look brave. Who'd gone missing in that forest?

"Who'd gone missing?" Sometimes I wondered if Harry could read my mind. She was looking up from her book at the table, her hair plaited back despite it not being a school morning. "Who'd snatch Johnny? Although I guess he's fat enough to be roasted –"

"Harry!" Mum and Aunt Petunia looked at her sharply.

"Sorry." She didn't sound sorry.

"It's mostly hikers, campers. People who stay in the woods overnight." Aunt Petunia looked out the kitchen window. "Not trying to scare you, Johnny. Just trying to warn you. Don't get lost, and get back before sundown."

"Aunty's right. Be a good boy, okay?" Mum kissed my forehead. "Mummy loves you."

I ran outside, to freedom and morning sunshine. The grass in the backyard was freshly cut and the summer flowers were blooming. Aunt Petunia's favourite pair of gardening gloves sat next to her trowel and watering can near the bed of roses.

There were dirt trails leading into the forest, and I ran down one of them with Uncle Billy's compass in my pocket. The trees loomed up over my head, and it still seemed to be early morning underneath the leaves, with the mist still hovering over the ground. I thought about the disappearances and shivered slightly, wishing I'd brought a jumper.

After a moment the spooks passed over and I looked around to find a tree for the treehouse. I didn't really know what I'd do after I found the tree, but since all the big adventurers had a tree house I thought I'd make one, too. I could pretend I was one of those big adventurers and hide from Harry's grumpiness in there. I'd make a big sign that said "JOHN WATSON'S TREEHOUSE NO GIRLS ALLOWED" in big red letters.

"Avast, ye mateys! Captain John Watson o' the Skulls n' Crossbones ahoy!" I was now a fearless pirate of the high seas, searching for booty and boats to plunder. Grabbing a small branch from the ground, I swung it about like a cutlass. "Captain John Watson don't take no prisoners! Drop yer weapons and prepare to be boarded!"

I stabbed a tree in the knothole. "Take that, ye scurvy dogs! Hiya! Hiya! Arr, shiver me timbers!" My knee wasn't hurting a lot by now, but I didn't want to take the plaster off. It'd only hurt again. I swung at the tree again, and started climbing. I scraped my right knee this time.

"Arr! Captain John Watson has found the treasure!" I bounced slightly on the branch and wondered if I could build anything on it. Uncle Billy's compass was a small weight against my leg.

There came a rustling from the nearby bush. Immediately I wasn't Captain John Watson, but just plain ol' John Watson again. A boy with light brown hair and an umbrella popped out of the bush, looked around, and popped back down once more. I frowned slightly.

"Hey, you! I don't think I've seen you before!"

"Shh!" the boy's eyes appeared from above the bush. He frowned at me. "Keep it down, won't you?"

I shut up immediately. The boy looked older than me, after all.

There came more footsteps from behind me. I turned around to see who it was, hoping it wasn't whatever giant monster that had taken the other people in the forest. My breath let out when I saw that it was just a boy who looked a bit younger than me. He was almost like a stick, a pale stick with curly black hair. He was dressed like one of those prissy posh boys who go to private schools – and come to think of it, the boy with the umbrella was dressed the same.

I frowned. He looked up and saw me, but I don't think he recognised me – and really, I didn't recognise him, either. He walked over to the side of the road and knelt down, looking at something in the grass. I tried to see what he was looking at. He nearly covered all of it.

The pale stick boy carried three bags, two of which were full of something and the third empty. He also had a magnifying glass in his hands that looked far too big for a kid. As I watched, he started picking things off the ground and looking at them through his glass. Some of them he tossed away. Others he put into the bag.

I was really curious about the boy. I could see the umbrella boy watching him through the bushes, too. He wasn't doing anything, though. The pale stick boy's bags looked really interesting, and I wanted to see what was in there. What was he doing? Why hadn't I seen him before? I leaned out to jump off the branch, but I leaned out a little too much and –

SLAM!

Pain burst everywhere, especially in my knees and hands. I kept my head to the ground, wondering how many band-aids it was going to take. I didn't like this morning, not at all.

I heard voices.

"Mycroft, what are you doing here?"

"Watching."

"Well, don't just stand there in the bushes and watch, get me bandaids and antiseptic!"

I heard the sound of the umbrella boy – Mycroft, was it? – running off and then there was a poke at my side.

"I'm fine," I muttered into the ground.

"No, you're not; you just sustained a fall from a branch four feet off the ground and you landed on all fours, which means that most of the impact was sustained by your knees and palms. There are rocks in the ground, so you may be bleeding. You're lucky your nose isn't, too. Because the dirt isn't exactly the safest place, it would be safe to deduce that you need first aid of some sort. Even minor cuts can get infected with the state of the ground like this."

Did all of that just come out of the stick boy's mouth?

"You're also lucky my brother Mycroft feels athletic this morning because he's usually a lazy sod." I slowly raised my head to meet the stick boy's amused face. His eyes were grey-blue. "The name's Sherlock Holmes."

"John Watson," I replied. Sherlock looked at my knees and palms; the knee scrapes had reopened but the palms only suffered bad dents from the ground.

"As I suspected. We'll have to clean and dress your knee."

"I know that," I muttered. "I fell down the stairs this morning."

"What was that like?" Sherlock asked, with all the curiosity of a scientist. I frowned at him.

"Hurt a lot. So you live in the big mansion, don't you?"

"Yeah. So?"

"I've been here every summer for the past nine years and I've never seen you."

"I'm five," he replied, as if it was no big deal. I frowned.

"You don't look or sound five."

"So?"

"So you're really tall and smart."

Sherlock tilted his head and stared at me for a long moment. Finally, he said again:

"You're rather popular at school because you're the fastest runner at break and everyone wants you on their team. However, you read and write a lot and you rather like writing. You're here to find a tree for a treehouse, but you have no idea how to build one. You imagine yourself as a brave explorer and you are prone to flights of fancy when you are in the forest, something that makes you love going here every summer to visit your aunt in the cottage next door. On the other hand, your sister detests the place because she can't bear a summer without her friend Clara."

I frowned at him. "How did you even…"

"It's very simple." As I leaned across the tree I fell out of, Sherlock sat down from across from me. "You have a callus on your finger from holding a pencil, and while that could also suggest that you draw I see no grey shadow on the underside of your pinky from past cases of excessive graphite. You're also wearing a Hardy Boys t-shirt, which suggests that you read their tales – interesting fellows, but they don't rely on deduction as well as I do so I can hardly look up to them. Your cottage and my house are the only houses in this particular area with any children, so I can assume that the girl I saw skulking in your garden earlier was your sister. I bumped into her as she returned from the woods; she carried a letter from a girl named Clara that had three kisses on it. When I saw you, you were sitting on the branch swinging your feet, looking around at the other tree branches as if assessing their strength for a tree house. There is a stick in your hand that obviously had been a prop from an earlier daydream."

"What about being popular?"

"Sturdy, strong legs, athletic build. No-brainer on that."

I thought it was quite the brainer. "Wow. That's really cool," I mumbled as Mycroft came running back with the first aid kit, wheezing as if his life depended on it. "Do you do that a lot?"

"Do what?" Mycroft asked.

"He looked at me and told me a lot about myself. I didn't say anything," I replied, pointing to Sherlock. Opening the kit, I grabbed some gauze and antiseptic and started cleaning my wounds, peeling away the old band-aid to be refreshed. "Does he do that a lot?"

"Every time he meets someone new," sighed Sherlock's older brother. "Drives my friends nuts."

"They always tell me to piss off," Sherlock added. My eyes widened slightly.

"That's not very nice," I pointed out. Sherlock shrugged.

"You're probably wondering about my collection," he continued, and I kept on wondering if he'd read my mind. "I'm a bit of a scientist, you see. I keep specimens. Right now I'm trying to collect all of the bugs in this forest – all of the different bugs, that is."

"Different species of bugs," corrected Mycroft.

"I'd like it more if you didn't spy on me all the time," Sherlock retorted.

"Can't I worry about you?"

"No. I don't need to be coddled, least of all by you."

Mycroft seemed to take it in stride. I thought of me and Harry, only with Harry in Sherlock's place. Mycroft started twirling his umbrella as I put my plasters on. Both knees, now.

"It's really weird. I've never seen either of you since now. Why now?"

"I try to stay in the house," Mycroft replied with a shrug. "Except now Sherlock's gotten bored of staying inside and wants to go outside all the time; I have to keep an eye on him."

"Oh." I frowned. Sherlock packed the first-aid kit. "Well, it's nice meeting you two."

"Indeed." Mycroft smiled, taking the first-aid kit from his brother. Sherlock collected his bugs. "It'd always be nice if we met up again throughout this summer. Sherlock's not the type to make friends easily, I'm afraid, but your company can do him wonders."

"Okay." I really had nothing else to say, especially since Harry had appeared waving at me. "Gotta go to lunch. We can meet up here in the afternoon or something! I'm sure there's… lots more bugs to collect…"

"We'll see," Mycroft said smoothly, taking his brother's hand. "Come along now, Sherlock."

And they walked off in the other direction towards their house, leaving me with two bandaged knees and a smile on my face.