User:OnceUponA BlackSwan

Odile (most known as Black Swan) is a caracter in the "Swan Lake" ballet. Daughter of Von Rothbart, she is the avarage woman from the romanticism movement beeing seen as the diabolical one: fatal, seductive, manipulative and deadly enchanting. Beeing a specialist in the dark magical arts, the witch transforms herself into Odette's look-alike so she can go instead of the white swan to Prince Siegfried's ball and make him propose to her. That way, Odette would be betrayed and would day, unlike what would happen if the real Odette went to the ball (Von Rothbart would die and all the swan would be free from his speel).

So, in the third act (the only one she appears in "Swan Lake"), she managed to have the prince proposing to her in from of Odette who was watch the scene from the palace window, since he can not understand who she really is under the perfect diguise. She is considered then the white swan rival: the Black Swan.