— Castor talking about Diana.
Over 2,000 years ago, Castor met and fell in love with a young handmaiden, named Diana. Although Castor and Diana loved each other, their love was highly forbidden, as Diana was engaged to be married to Darius, a Demonic Sorcerer. Diana’s father had promised his youngest daughter to the Sorcerer in return for his family’s safety. Due to the circumstances, the relationship between Castor and Diana was kept in secret and the couple had to secretly exchanged vows. However, the couple were betrayed by their confessor and had to flee. In his insane jealously, Darius made a demonic pact to ensure that they would be "Always together; eternally apart”. By day Diana becomes a hawk, and by night Castor becomes a wolf. Neither has any memory of their half-life in animal form. Only at dusk and dawn of each day can they see each other in human form for one fleeting moment, but they can never touch until Diana surrendered herself to Darius. The curse would only be lifted if there was "a night within a day".