The Sorceress of Colchis
Medea is the daughter of Aeetes, king of Colchis, and a niece of Circe — magic runs in the family. When Jason arrives for the Golden Fleece, she falls for him and uses that knowledge against her own father, drugging the sleepless serpent that guards the fleece and helping the Argonauts escape at a cost that includes her own brother's life.