Colin Moriarty is a crime boss in Megaton, and is the owner of 'Moriarty's Saloon'. Colin is probably the wealthiest man in the town, and his father emigrated from Ireland, hence the surname.
If you read the terminal in Moriarty's Saloon you can read Colin's thoughts on Billy Creel. He believes Billy was a slaver who killed Maggie's parents and kept her as a trophy
 Following in His Footsteps
- Main Article: Following in His Footsteps
In the quest Moriarty has information regarding your father. You can pay him, pass a speech check, break into his locker, or convince his workers to tell you. If you do not have enough Bottle Caps Moriarty will assign you the unmarked quest;
 300 Pieces of Silver
- Main Article: 300 Pieces of Silver