The Great Game.
Jim had known Sherlock for as long as he could remember. Ever since he killed that boy, Powers, he and Sherlock had been practically inseparable. He thought he'd never get caught, until one day, the boy in the long coat swanned into his life, and solved the murder. The police didn't listen to him, obviously. An eight year old boy solves a murder committed by an eleven year old boy? Poisoned shoes? 'Never heard such bollocks.' Their words, not his. Jim would never criticise him like that. Because Sherlock was too much like him. Sherlock was clever. He was special.
With Jim unable to commit a crime Sherlock couldn't solve, and Sherlock being ridiculed and ignored by the local police, it had seemed the obvious option;They'd work together- Jim committing the crime, Sherlock solving it, but never catching Jim. Sherlock had become an international celebrity for his great intellect and powers of deduction before he had finished his sixth case. Jim was able to commit whatever crime he so chose, and frame anyone he wanted for it. Not that Jim did the killing. Not often anyway. He rather liked his well tailored suits, and it would be such a shame to get blood on the Westwood. If Jack The Ripper was a smooth criminal, Jim was a velvet crime lord. His vast network made him impossible to trace, his crimes so intricate, they were impossible to solve. (Unless, of course, your name is Sherlock Holmes.) He could disappear in an instant, he could never be traced, and should all else fail, he had a brother who would happily take the fall for him, and be grateful for the chance to serve his brother. And Sherlock? He got his dream. He got to deduce and solve and be every bit the genius Jim knew he was.
It was all going so well. And then, he happened.