Watson tries to have a private life once he starts living with Sherlock, but Sherlock often intrudes or forces him to cancel plans.
They are often mistaken for a gay couple, which Watson attempts to protest the first few times before giving up.
He becomes very attached to Sherlock and eventually considers him his best friend. He frequently is forced to apologize or explain Sherlock's brusque manner and abruptness.
He occasionally acts as a go-between, not always willingly, for Sherlock's brother, Mycroft Holmes, as he attempts to corral or protect his brother.
He has an older sister named Harriet, whom he calls "Harry." She's an alcoholic. He was trained at St. Bartholomew's Hospital as a British Army doctor and served as a Captain in the Fifth Northumberland Fusiliers. He was shot in the shoulder while serving in Afghanistan. When he returned, he began seeing a therapist for Post Traumatic Stress syndrome. When he meets Sherlock Holmes he has a limp, which Sherlock quickly announces is psychosomatic.