Synthetic

Written for the prompt on the Sherlock kink meme here: John is the best blade runner ever to have worked for the London police. Mycroft calls him out of seclusion to track down and retire one especially slippery replicant that used to be an invaluable asset to them in solving crimes, but over time began to believe that it was human. This replicant’s mind has deteriorated to the point where it now believes that Mycroft is its brother, and that it is a consulting detective.