Galatea is actually a clone of Supergirl, created by Professor Hamilton and Project Cadmus and artificially aged to adulthood. She is designed specifically as a countermeasure to the Justice League, more specifically Superman and Supergirl, in the event they were to go rogue. Galatea's personality has been altered to ensure she performed her duties with a sociopathic relish. Due to the quirk of the cloning process, Galatea and Supergirl share a psychic link which allows Supergirl to experience Galatea's actions while sleeping, while Galatea experiences insomnia due to Supergirl's subconscious moral restraints on her own actions.