He is the leader of the Order of Atomguard. Fallout lore specifies one fanatic church, the children of atom who worship radiation as a god. If you think children of atom as christianity, Atomguard is like a hardcore Spanish inquisition, an armed force out there to anihilate heretics and that also includes "the false atom", vampires. Hagen is the definition of that ideology, ascended by being the most fanatic of the fanatics.(edytowane)