He is a soldier returned from the war who finds himself sharing a flat with Sherlock Holmes. He is addicted to danger, and follows Sherlock where ever he goes on the promise that danger will be present.
He is often picked up by Mycroft Holmes to pick up cases for Sherlock, or for Sherlock's brother to enquire after his little brother, because Sherlock won't talk to him himself.
John in loyal and trusts Sherlock compleatly. During the first episode he shoots a man when he sees that Sherlock's life is in danger. Sherlock begins to describe the shooter to Lestrade then cuts himself off when he realises that it's John.
John begins to date a Doctor at the hospital, Mary, but it seems like the relationship has vanished after the first series, following with a number of other girlfriends, the last one who is convinced that John and Sherlock have something going on between them.
"You know, my friends were wrong about you. You are a good boyfriend.... And Sherlock Holmes is a very lucky man"
John often grows irritable and tired of telling people that he and Sherlock aren't a couple.
He is kidnapped by Moriarty as the last victim of the bombings, and is presented to Sherlock with a bomb strapped to his chest. The moment Moriarty leaves Sherlock tears of the bomb and throws it as far away from them as possible.
In the second series, John encourages Sherlock's relationship with Irene Addler, believing it to be healthy for him. He grows angry at Irene when he realises that she is still alive when Sherlock thinks she's dead, forcing her to text Sherlock to let him know that she's alive.
By the end of the episode he believes Irene to be dead.
In Hounds of of Baskerville he and Sherlock are called out to Devon. He has an argument with Sherlock after Sherlock snaps at him that he doesn't have friends. Sherlock later apologises, assuring John that "...I don't have friends... Just one."
Even so, Sherlock later terrifies him during a test, causing more hostility between them.
John remains compleatly loyal to Sherlock through the whole ordial when Sherlock is accused of being a fake, refusing to believe the accusations are true. When Sherlock is arrested he punches the arresting officer, being arrested himself.
Sherlock throws himself off the top of the hospital to protect John amongst others. Phoning John with his supposed Suicide note, telling him that it was all true and that he was a fake. John still refuses to believe this.
After Sherlock's supposed suicide, John confronts Mycroft blaming him for the death of his brother.
It is revealed at the end of the episode that Sherlock is not dead, but John still views him to be so.
- He has a homosexual sister
- He fought in the modern Afghan war
- John is faster to lose his patience with Sherlock than the original
- He is also portrayed as more intellegent than the original Watson in the stories
- Although he dates a Mary, he does not marry her, and he seems to have broken up with her between the first and second series.