Mycroft was playing house in the nursery, his mother's old doll's house open in front of him.
This was one of his favourite games, making pretend tea and scones on the stove. Serving said pretend tea and scones to the well dress dolls sitting neatly round the table in the dinning room. While upstairs the maid was making the beds and packing away the toys.
Sherlock however was on his rocking horse, imagining it as his very own pirate ship, and doing so very loudly.
Sherlock gave a victory cry as a wod of chewed up paper flew from his slingshot and into the doll's house, knocking over Timmy, the eldest son.
Mycroft froze, staring daggers at Sherlock in his mind's eye. After a moment he collected himself, picked up Timmy and carried him off carefully to the wash room to get him cleaned up.
Sherlock waited until the door of the nursery had closed before dismounting and heading over to the doll's house to claim his treasure.
Sherlock wasn't interested in the dolls, nor was he interested in moving around any of the furniture, because although that would really annoy his big brother, he would also be letting himself in for weeks of Mycroft trickery, which was not really all that worth it. No, what Sherlock was after was much better. Sherlock was after blackmail.
In each room of the doll's house there was a little chest. Mycroft had painstakingly saved up his pocket money for months to by each one. Repainting them all by hand so that they would each match the interior of each room.
And inside each chest there was a singular piece of paper, and on each piece of paper in Mycroft impeccable hand Sherlock's brother had written in tiny doll sized writing his inner thoughts.
Sherlock picked the lock of the chest in the larder; this was the chest that Mycroft tended to keep his more embarrassing secrets in, things that he had let himself indulge in that he later regretted.
The young pirate skimmed past the first few entries, these he had read before and had already committed to memory, though he let himself re-read the third entry, as he always did, never really quite believing what he read, translating the short hand easily in his head. "Used the word toilet instead of lavatory. Mother didn't notice" Sherlock giggled, his brother was so strange.
There was only one new entry on the list today, "Kept holding Jane's hand for a minute after crossing the road" Sherlock frowned, how was that something to regret?
He was so puzzled over this that, he didn't notice Mycroft returning from the wash room.
Mycroft wasn't cross, not really. He knew Sherlock had read the notes he left in the chests. He'd worked that out months ago, and so had started to leave notes that might help in Sherlock's moral development; he also uses various types of short hand in order to make Sherlock learn the different types.
He was however disappointed. Disappointed that Sherlock would be so blatantly obvious in his snooping.
Mycroft coughed to draw Sherlock's attention to his presence, which resulted in Sherlock stuffing the piece of paper into his pocket and the chest haphazardly back into the house.
At this Mycroft sighed and looked even more disappointed. "Poor cover up brother dear." He sighed as he moved to the doll's house and straightened the chest. "I know you read them. You really think I would be that slow to write anything incriminating down in there. No I keep that sort of thing up in this house." As he said this Mycroft tapped his temple.
"You have a house in your head?" Sherlock asked clearly amused at the absurd notion.
Mycroft just smiled patiently and explained, "I call it a mind palace, I imagine this doll's house, each room is for different thoughts. The master bed room is for everything regarding Mother and Father, their birthdays, wedding anniversary, fears, medical information and the like. The box room is yours, so I keep all your relevant information in there. Then there are rooms like the library where I store useful quotes and sometimes whole books if necessary. You get the idea."
Sherlock's little face brightened as he understood what his big brother was trying to tell him. Mother and Father's brains could not retain as much information as his brother's and his own, so they had not seen the need to teach Sherlock how to properly order his thoughts. But Mycroft knew, he knew was it felt like to have a million thoughts flying around in your head, and having to catch them and pin them down whenever you wanted to use them.
If he could somehow order them into boxes, and organise those boxes into rooms it would take mere milliseconds to locate the relevant thought.
Sherlock beamed at Mycroft. He was going to one up his brother. He wasn't going to have a mind palace. Oh no. He was going to have something much better. He was going to have a mind pirate ship!
And with that Sherlock shoved the piece of paper into Mycroft's face and climbed back onto his rocking horse pirate ship, as began to order his thought about the S. S. Sherlock Homes.
Author's Note: I don't own Sherlock