He is portrayed by Robert Duvall in the films. He operates as the consigliere and as a lawyer for the Corleone family , and is an informally adopted member of the family. He is a lawyer and the consigliere to the Corleone American mafia family. Logical and gentle, he serves as the voice of reason within the family.
The novel and first film establish that he is of German - Irish ancestry. Vito's eldest son Santino James Caan befriends year-old Tom, who was living on the street after running away from an orphanage. When Sonny brings Tom home and demands he be taken in, the Corleone family welcome him as a family member.
Hagen considers Vito his true father, although Vito never formally adopts him, believing it would be disrespectful to Hagen's deceased parents. After law school , Hagen goes to work in the Corleone family business. His non-Italian ancestry precludes his formal membership in the mafia family, but when the consigliere Genco Abbandando dies, Hagen is given his position.
Hagen immerses himself in the Sicilian-American culture and speaks fluent Sicilian. His Northern European appearance, though distracting to the Five Families, is an advantage to his job. He is able to travel and conduct family business in non-Italian circles without potential witnesses noticing him.
While Hagen loves all the Corleones, he is closest to Sonny, and blames himself for Sonny's murder. When Vito semi-retires and his youngest son Michael Al Pacino succeeds him as the head of the family, Michael removes Hagen as consigliere , preferring his father informally assume the role; Michael claims Hagen is "not a wartime consigliere ".
