Sean Nast is a Sorcerer and member of the Nast family and it's associated Cabal. His father is the late Kristof Nast. He has two siblings, Bryce Nast and Savannah Levine. He is the only one in his family who acknowledges his sister. He is gay, but when he told his uncle he said that everyone had figured it a long time ago, and to just keep quiet about it and get married. And that the Nasts don't care what he does on the side, but he has to have kids. Sean thinks to himself that he won't just get married, but that that is a battle he will fight at another time. He gets along rather well with his sister, and her foster parents, Paige Winterbourne and Lucas Cortez.

At the time of the novella Atoning he was twenty nine, as Atoning was set 4 months after the events of Spell Bound and 13 he can be assumed to have also been 29 during those novels.