The youngest executive of Manhattan's Martillo Family Camorra. Firo is surprisingly friendly, humorous and compassionate, but he is a skilled fighter and can be ruthless or even vengeful towards those who bring harm to the people he cares about. He became a complete immortal in November 1930 after accidentally drinking Szilard Quates' immortality elixir. In the same year he falls in love with Ennis, and despite the fact that she initially is unsure of her affection due to her underdeveloped emotional capabilities, they live together as roommates and gradually she reciprocates Firo's feelings.
