This is kid!Sherlock and kid!John Story. It's pre-series and slightly AU.
In the first chapter Sherlock is eight, John ten and Mycroft fifteen
It was cold. John put his right hand in his pocket, but he was still writing his homework with his left hand. He was sitting on a bench near a playground as he did every day. It wasn't a particularly nice playground, but John new that his father never walked through this park. It was a quiet place except for the few sunny days when a crowd of kids came along with their moms who would watch them play while exchanging the latest gossip. Sometimes they would talk to John and praise him because he was doing his homework and even give him a few cookies and orange juice. John liked that, but it only happened a few times in summer. Most of the time, the park and the playground were lonesome.
Today nobody was there except for John and a young boy who was probably two years younger than him. The boy had curly black hair and was sitting on the swing. He didn't look like he was enjoying himself. He looked much more like he was sulking. But John ignored him. He just wanted to do his homework.
John wasn't a wealthy boy. His family was actually quite poor. One couldn't consider his family to be happy too. John's mum had left. John couldn't even remember when and why but he guessed that her disappearance had something to do with the fact that his dad was an alcoholic. He was an angry and sad man. John knew that his dad hadn't been always like that. They had a lot of smart books at home who belonged to that man, but John hadn't seen his dad read anything for ages. Usually his dad was away drinking. Sometimes he slept all day. A few times a month John actually talked to his dad and it never ended well.
But there was also John's Sister Harry. She had been lovely the past few years. She had always made breakfast and dinner. She worked part time and paid for everything John needed.
She still worked and she still paid for their bills but a few weeks back something changed. It first started when she had a new boyfriend. She came home late and woke up John. She reeked like John's dad did when he came home from a pub. John always got scared from the smell of alcohol, especially whiskey his dad's favourite drink. When she told him that he had to sleep on the couch tonight he obeyed without asking. Young John didn't have a bed of his own. He shared a bed with his eight years older sister. But that was fine. He liked to have her near him.
After that day Harry started to sleep in late thus John had to make his own breakfast and she usually wasn't home until late in the night, so most of the time John went to bed without dinner.
In school nobody knew about his family. John was a really good student. He was prepared, attentive and curious. The head master even asked him if he would like to skip a class.
It was getting dark and John had just thought about going home, when it suddenly started to rain. John cursed quietly, packed his things and ran into the small wooden house on the playground. It was shaped like a boat and John remembered that the kids in summer always pretended to be pirates when they played on the boat.
The small house wasn't comfortable, it was dirty, full of sand and smelled a bit like piss but it was still better than getting soaked by rain.
The small boy with the curly black hair joined John. Without saying anything he sat down in the other corner of the room. Both of the boys looked out of the door and watched how the rain got stronger.
John felt a bit awkward. He felt like he was supposed to talk to boy since they were in the same room alone. But the little boy didn't seem to bother.
But the little boy cringed when a loud thunder clapped on somewhere not too far away.
"Aren't your parents worried? It's nearly seven o' clock. You are a bit too young to be at the park alone when it's getting dark." John said to the young boy.
The boy narrowed his eyes.
"I'm eight. You don't look much older. So don't pretend to be older."
"And I am ten. Eight and ten is a difference." John argued.
The boy snorted. Suddenly John thought that the boy didn't seem to be that young anymore. Sure, he was young but something told John that the boy was pretty mature for his age.
"So what are you doing here at this hour? Why aren't you at home? No dinner at home?" John asked. Maybe the young boy was in the same situation like he was. Maybe that boy had an alcoholic father too. Maybe he understood John and maybe they could be friends.
The boy shrugged his shoulders.
"I don't want to be at home. My parents are away for two days and they left me with my brother."
"So what's the matter? Is your brother that bad?" John asked.
"Yes. He the most evil person one can encounter." The boy said.
John smiled. The brother surely couldn't be that bad.
"What did he do?"
"I don't want to talk about it."
"Did he beat you?" John guessed. There was compassion in the older boy's voice.
"No."
"Did he forget to make you breakfast and dinner?"
John thought about Harry. She had forgotten about him the entire week, but John understood her. He wasn't angry. It had to be hard to work and take care of her younger brother.
"No. He always makes me eat."
"Did he wake you up in the middle in the night and told you to sleep on the couch?"
"Why would anyone do that?"
John shrugged his shoulders.
Again both boys got silent and watched the rain fall. The rain wasn't going to stop anytime soon.
After a while the young boy finally told him what happened.
"He called me stupid." He said. "My brother told me that I am stupid, but I am not."
John started to laugh. This surely was a funny boy. He had been sulking alone at playground for hours because his brother told him he was stupid.
John knew that the boy didn't have the problems he had and somehow he felt relieved. It wouldn't make him happy to know that he wasn't the only one with an unhappy family.
"What?" The young boy asked confused but angry too.
"Nothing…" John said still laughing.
"I am not stupid!"
"Yeah, I think you are not. But this is what older brothers do. They call you stupid. It's like their job."
John explained.
"But that doesn't make sense!"
John smiled at the boy.
"What's your name? I am John."
"Sherlock. Sherlock Holmes."
Funny name, John thought, but he didn't say anything.
"Did you finish your homework?" Sherlock asked out of nowhere.
"I have everything what is due to tomorrow. How did you know that I was doing my homework?"
John asked a bit surprised.
"I think it was quiet obvious." Sherlock answered. John thought about it for a minute and nodded.
"But you haven't finished math yet, have you? You had a few problems, didn't you?" Sherlock guessed.
"How did you..?"
"I can help you! I am bored. Math can be fun."
"But I am older than you. It might be too difficult for you."
"Unless you have started with integral calculus, it will not be too hard for me."
Unbelievingly John showed Sherlock his homework, but it seemed that Sherlock actually understood it.
"You really can't solve that one?" He asked.
John nodded and listened to the boy as he explained him how to solve it.
They've been working on his homework for half an hour when they heard someone shouting: "Sherlock! Sherlock!"
John looked out of the house and saw a teenager, probably about fifteen. He was coming closer to the boat house. It was still raining heavily but he had an umbrella.
Sherlock rolled his eyes. "That's my brother. I hoped he would let me alone a bit longer."
"He doesn't look that bad." John said.
"He is, believe me."
"Sherlock!" The older boy shouted again. He was now standing in front of the house. He glared intensively at John, but he couldn't scare him. John's dad was far scarier.
"Sherlock, I know you are in there. Don't make me climb into that filthy thing. Come out. Dinner is ready." Sherlock's brother explained. John somehow envied Sherlock. Although Sherlock's brother wasn't all too friendly he still seemed to care. And John was hungry. He would love to have dinner now.
"Yes, alright. I'm coming." Sherlock climbed out of the small house. He ran too his brother. The teenager put an arm around Sherlock. But before the Holmes brother walked home, Sherlock turned around to John.
"See you, John."
"See you, Sherlock."
After Sherlock had left John tried to read in his textbooks until it was too dark. At some point young John fell asleep. When he woke up it was still dark, but the rain had stopped.
At home he found that his father was already snoring loudly in his bedroom and his sister was asleep too. There was a guy with her in bed hugging her. She was naked and John felt awfully embarrassed as he saw her bare breast.
He wondered if anyone had even noticed that he hadn't been home for the better part of the night.
John found that his stomach was growling. He looked in the kitchen for food but expect for a few beer bottles there was nothing. He was really hungry and thought about how his dad sometimes only had beer for dinner. Maybe he should try it since everyone in his family seemed to drink. His dad had once explained that alcohol numbs pain.
John opened a bottle took a sip, but spat it out the next second. How could they drink that? It tasted as bad as it smelled. Angrily John emptied the bottle above the sink. He thought about empting the other bottles too but in the end his dad or his sister would just buy new ones and there would less money for more important things like food.
John went to the couch. He threw view empty bottles and someone's clothes onto the floor to make room one the small couch and lied down. He didn't have a blanket, since he and his sister normally shared one big blanket and he really couldn't just take the blanket from her and that guy. So he covered himself with his coat.
Although he was hungry and cold he fell asleep pretty fast. That night John Watson had view strange dreams.
He dreamed about Sherlock being his brother. He dreamed about how that older boy didn't only come for Sherlock but also for him and how they had a nice dinner and how he and Sherlock continued doing math before their older brother sent them to bed.
But when John woke up the next morning he was still in the small apartment. His dad and sister were still asleep in the other room. John hurried up and went to school. If he was there early he might have time to help the cafeteria staff to carry in the food which got delivered in the morning and he might get something to eat for free.