Author's Note: The prompt was Letters. Enjoy.
Hide and Seek
Sherlock had gotten his first letter from Mycroft when he was nine.
It was handed to him directly, no postage. His name was written on the envelope perfectly in Mycroft's familiar scrawl. There was no return address. It was almost annoying and a bit nerve wrecking. The letter it held was short, not revealing anything, but it was the post script that caught his attention.
"I know you're bored, Sherlock. I have left some clues. Do your best to send me a letter. You have three days."
It was thrilling. Sherlock had torn through the house, looking and analyzing everything he could. In three days, Mycroft returned to a frustrated Sherlock.
Sherlock was playing his violin when he received the next letter. He was fourteen.
The letter was made of cheaply bought stationary paper - something that Mycroft would never buy himself, but the handwriting was unmistakable. He thought back to his first letter, and the message was similar.
Five Days. Send a letter."
It was like hide and seek on a much bigger scale. He searched harder this time. Myroft was efficient in how he gave clues - he must have set it up carefully to give Sherlock just enough information, but not enough at the same time.
Completely and utterly frustrating.
But Sherlock was smarter now. He sent his letter on the third day.
Mycroft greeted him two days later with a smile on his face and a 'good job.'
There had been many letters in between. A childish game of hide and seek between Mycroft and Sherlock. As Sherlock became older, the letters began to simply state the number of days he had to find Mycroft and send a letter.
It was amusing while he was in between cases.
The most recent letter came when he and John moved into 221B. Mycroft had been in London at the time, so why...?
He brushed his hand across the front of the envelope. The strangest thing - there was a return address, though the stamp was still missing. He opened it carefully, sliding a fingernail under the seal and reading the letter carefully.
"Be good to him."
It was signed, unlike the letters had been for the past few years. He glanced up at John, whose brow was furrowed in curiosity. "Let's go," was Sherlock's only response and he tucked the letter in his coat.
It was the last letter he received from Mycroft.
That didn't save him from the visits though.