DO NOT READ UNLESS YOU'VE WATCHED SHERLOCK SEASON 4
I don't own the characters or the show, sadly.
All characters belong to BBC
He wasn't supposed to tell Sherlock his secret. That he was not, in fact, John Hamish Watson, but another man. A man that Sherlock had once known, when he was just a child. It had been easier to tell the dark-haired boy lies instead of knowing what truly happened. If Sherlock thought that Eurus was a shock then he was about to have a heart attack.
It would be dangerous if Sherlock knew who he truly was, only Mycroft and 'John's' parents knew his true identity, not even Lestrade could dig deep enough to figure it out. Mycroft destroyed his files and gave him the background of John Watson.
But now it was time to tell him, tell Sherlock his darkest secret. That he was Victor Trevor... He was Redbeard and he was his brother. He never died in the well, he climbed out with bloody hands and blisters to Mycroft who hid him away until he joined went to medical school and the army under a new name.
When Eurus told him that it wasn't a secret brother but a secret sister, he almost scoffed. So Sherlock had a secret brother and sister. John was the second oldest Holmes child, he was a year older than Eurus and 2 years younger than Mycroft.
Sherlock's deductions were only correct because that was how John and Mycroft set them to be. He gave John the scratched phone and told him to fake a limp, the tan lines were the only real thing that Sherlock knew about him. John had the phone engraved with fake names to throw him off. Harry was originally going to be his brother but he thought he'd have some fun and said that Harry was short for Harriet.
He was ripped from his thoughts as the flat door opened and Sherlock strolled in. He glanced at John who was sitting in his chair with a furrowed brow.
"You have something on your mind," Sherlock stated. John looked up and opened his mouth to speak but quickly shut it
"Tell me, John," Sherlock ordered.
"Mycroft wasn't the only one hiding something from you,"