Patrick "Sully" Sullivan had been a crime boss in Boston before the events of the show.  When first shown, he is living in hiding after Mickey Donovan betrayed Sully's crew - which included members of Sullivan's family - to the authorities. When Mickey is released early, Ray convinces Sully to come out west and kill him, believing that Mickey's earlier betrayal will be reason enough.  Unknown to Ray, Sullivan also blames Mickey for the murder of Colleen Dawson, a young woman that he had fallen in love with.   Before Sullivan can kill Mickey, Ray's father reveals the truth - that Colleen had been murdered by Sean Walker.  Sullivan is convinced, and releases Mickey Donovan.  He also brutally murders Sean Walker.