John Watson was too focused on his school work, being a half-blood raised in the muggle world he had never seen anything like his studies before, so he never really got time to fit in with other Gryffindor's, let alone outside of his house. He did however become fast friends with a group of Gryffindor's that called themselves 'the Marauders', they were 2 years older than him. This didn't stop them from helping him with his homework, well Remus and David helped him the other 3 just messed around.
When he graduated he decided to join the muggle army and he went off to Afghanistan to fight on the front line. He came home after being shot in the shoulder. Now he had a limp and serious psychological issues. He had had his wand removed from his care until he got over it. His mother hadn't thought he had a gun so she didn't take that. That day, after a visit to his psychiatrist, he was very close to shooting himself with that gun. A blog, his psychiatrist had told him to write one, was the last thing on his mind. He really needed to get a flat, and an army pension wasn't going to pay for one, nor were his Galleons that he had got from the Marauders after school. Harry had said she would help him, but he had refused he needed to do this himself.
Later on that same day, John was walking through the park when he was shouted.
"John?" Mike had said. Mike had been a friend of his in college before he joined the military. "John is that you?"
"It's me," John said, holding his hand out and looking confused.
"Mike," Mike said. "Mike Stanford." He took John's hand.
"Oh, right," John said.
"Last I heard you were overseas getting shot at," Mike said. "What happened?"
"I got shot," John stated gesturing with his cane.
The two sat and caught up for a short time before the topic of housing came up. "I don't know Mike, who'd want to share a flat with me?"
"That's funny, you're the second person to say that to me today," Mike said.
Still Later that day, Mike introduced John and Sherlock at St. Bart's. Somehow Sherlock knew everything about John, bar one small detail. Excluding the fact he was a wizard, as not even Sherlock would be able to guess that.
After a while John decided to correct that detail, "Harry's short for Harriet." John never told Sherlock of his actual history, well until he did...