Diego has made a lot of mistakes in his life. The first, and arguably the worst, was to be born at all; Diego's mother was a member of the Pack, a close-knit group of raiders following a "survival of the fittest" ethos. He was seventeen when the raider factions, united under Overboss Colter, seized control of the Nuka World theme park west of Boston, claiming the surrounding area and enslaving much of its population. It was here that Diego made his second error: issuing an audacious leadership challenge to the Pack's "alpha", Mason. Mason was still in his physical prime, and was commonly accepted as the most ruthless alpha the Pack had had in years. Diego was a scrawny nineteen-year-old, with more confidence than his skills warranted. Pack law forbade the killing of other members, but Diego was still lucky to escape with his life - although not before Mason made an example of him in front of his peers.
Humiliated and exiled, Diego went on to make his third mistake: he returned to Boston and joined a group of raiders, operating out of the old Corvega assembly plant in Lexington. Unlike the Pack, these raiders had no code of conduct and no loyalty to one other. Their goals were similarly chaotic - the group's leader, for example, had a particular interest in clairvoyance, in particular a Quincy woman called Mama Murphy. Diego and his fellow raiders managed to corner the Quincy survivors inside Concord's Museum of Freedom, but were subsequently driven back by an unknown assailant - not before Diego was incapacitated by the group's leader, Preston Garvey. Faced with the option of killing Diego in cold blood, Preston and his fellow survivors instead decided to take Diego with them as they searched for a place to settle.
Since then Diego has been kept under lock and key, as the survivors work to rebuild nearby Sanctuary Hills. Diego is good with his hands, and his advice has proven invaluable in keeping the settlers safe from raider attacks. The more time he spends in Sanctuary, the more Diego comes to value the broken-down settlement and its ragtag assortment of civilians and refugees. However, his time running with the Pack has left him with a lot of behaviors that he must unlearn if he wants to fit in. With the Nuka World raiders pushing into the Commonwealth for the first time, it remains to be seen where Diego's loyalties ultimately lie.