He and his sister Marcia Leone are refugees at Fort Atlas after their parents were killed in a raider attack. Max idolizes the Brotherhood and sees them as heroes, wanting to become a member to fight off threats to others. He believes the Brotherhood will save the world, but also likes the power armor they utilize.
↑Vault Dweller: "Can you tell me more about you?" Maximo Leone: "Oh, well my name is Maximo! You can call me Max though, for short. My big sister, Marcia, and I live here now with the Brotherhood. Isn't that cool?!" (Maximo Leone's dialogue)
↑Vault Dweller: "Why do you live with the Brotherhood of Steel?" Maximo Leone: "Well... the town we lived in got attacked by Raiders and our mother was killed. Luckily, the Brotherhood of Steel was there and they saved us! Since we didn't really have anyone anymore, Paladin Rahmani had us come along with them. I can't wait to become a member and fight off bad guys like they do. I'll make sure no one ever has to die again." (Maximo Leone's dialogue)
↑Vault Dweller: "What's so great about the Brotherhood?" Maximo Leone: "They're heroes! The Brotherhood is going to save humanity and help make the world a better place. They saved my sister and me, and a bunch of other people along the way. Plus, the Power Armor they get to wear is SO COOL!" (Maximo Leone's dialogue)
↑Vault Dweller: "What do you think about Paladin Rahmani?" Maximo Leone: "She's the leader of the Brotherhood and I'm going to try my best to impress her, so that she makes me a Initiate one day. It was Paladin Rahmani's idea to let us stay here with them, and I'm so happy that she did!" (Maximo Leone's dialogue)
↑Vault Dweller: "How do you feel about Knight Shin?" Maximo Leone: "Knight Shin is SUPER COOL. Have you seen his Power Armor? He doesn't really talk to me much, but I think it's just because he's super busy doing Brotherhood stuff and fighting bad guys. Plus he's usually hanging out by the weapons and I'm not allowed to go near there. I think we're going to be best friends one day though." (Maximo Leone's dialogue)
↑Vault Dweller: "What are your feelings on Scribe Valdez?" Maximo Leone: "Odessa is the best! She's super smart and is always saying stuff that I don't really understand, but I'm gonna study really hard. Sometimes when the others aren't around, we play hide and seek around the Fort." (Maximo Leone's dialogue)
↑Vault Dweller: "Why do you call her Odessa instead of Scribe Valdez?" Maximo Leone: "She told me I could because we're friends! Just like how you can call me Max instead of Maximo. Although, when I'm a Knight I would prefer it if you called me Knight Max." (Maximo Leone's dialogue)