What is the backstory of the character Harry, and how does he fit into the John Wick storyline?

Harry is a character in the John Wick film franchise, played by actor Dean Winters. He is an old friend of John Wick and a fellow assassin in the world of the films. Harry's backstory is not explicitly shown in the movies, but it is hinted at in a few scenes. It is suggested that he and John Wick have known each other for many years, and that they have a deep respect and loyalty for each other. In the first film, Harry is tasked with cleaning up the mess that John Wick makes when he goes on his revenge spree. In the second film, Harry provides John with some key information that helps him in his mission. Unfortunately, Harry meets a tragic end in the second film at the hands of another assassin.

Harry is an important character in the John Wick storyline, as he provides a connection to John's past and helps to establish the rules and customs of the assassin world in which the films take place. Additionally, Harry's loyalty to John serves to humanize the otherwise brutal and ruthless world of the films.