Arthur Morgan was born in to Beatrice and Lyle Morgan. His mother died when he was very young, and his father was a petty criminal and outlaw, who was arrested for larceny in when Arthur was 11 years old and along with his younger sister's Nora Morgan , Yevette Morgan and Emily Morgan. At some point, Lyle was killed and Arthur witnessed it, donning his hat afterward. Viewing him as a surrogate father figure, Arthur came to share Dutch's vision of a life lived free from the constraints of civilization and the rule of law, becoming one of the first members of the Van Der Linde gang.
At some point during his youth, Arthur met a girl named Mary Gillis and the two were deeply in love. However, Arthur's preference for a life of crime and the prevalent disapproval of Mary's family caused their relationship to fall through. Later around , Arthur would ask Hosea for the money to purchase a horse named Boadicea.
The two grew a strong bond together and went on various journeys and adventures, although she was let go during the Blackwater Massacre and Arthur was unable to recover her. At some point later, Arthur met and slept with a young waitress named Eliza, resulting in her becoming pregnant with their son, Isaac.
Eliza knew what Arthur was, but accepted whatever support he offered to her and their son, as well as personal involvement in their lives. Arthur would visit Eliza and Isaac every few months and stay with them for days at a time. One day, Arthur arrived at their home and saw two crosses outside.
Arthur knew immediately that they were both dead, and later learned that they were killed by robbers, all for ten dollars. The incident hardened Arthur ever since and he never truly coped with the pain, As he later saw his sisters leave the gang after they got married and went to live with their husbands and start their own families.
