Who is Charley Ford from The Assassination of Jesse James by the Coward Robert Ford and what is their importance?

Bob's brother, Charley is less intelligent but endears himself to people by pointing out his shortcomings long before they can become apparent. Charley is with Jesse for days prior to Jesse's death and is part of the gang that participates in robberies. Charley is in the home with Jesse when Bob shoots him. Charley stands by Bob after the shooting but eventually turns on Bob, saying that his shooting Jesse had been cowardly. Charley becomes ill after Jesse's death and eventually commits suicide in his parents' home.