Leo Montez is the oldest child of vampire Rayne Montez and human Nathan Montez. He has an aunt named Charlotte Fellington and two siblings named Loni and Anthony. His best friend is Blight Katoptris. It is made known that he has a requited crush on her.

Leo is a moonchild, the dhampir of the Sorceworld. He later turns into a Hatopis, much to his displeasure.