Well, so far, this is what I've come up with for both characters on the fly.
Leviathan - Comes from a wealthy family, and used to live in California near the beach. Still planning as to why he moved to New York City, but I'm thinking that he has an older brother who the family loved more, so Levi became envious, and decided to move all the way across the country out of spite. He's of Norweigian and Spanish descent, his mother's side of the family being Norwegian, and his father's side being Spanish.
He would have moved to NYC at the age of 21, probably went to film school. So he's been here for nine years.
Andras - Born and raised in NYC, the only child. Due to his violent temperament, I can't see him as having a lot of close friends. I'm picturing his descendents from Ireland, and or Scotland. As for occupation I'm thinking he's a bouncer at some club.