The Black Swan by Mercedes Lackey
The story of Swan Lake has enchanted generations: a monumental tale of loyalty and betrayal, of magic used for good and evil, of love both carnal and pure, and of the incredible duality of human nature as Prince Siegfried, a selfish hedonist and dissolute womaniser, comes across the swan maidens as day dissolves into dusk ...And then the woman he has wronged teaches him a lesson that will change the course of his life for ever ...Mercedes Lackey uses her own brilliant storytelling to breathe vibrant new life into an old favourite.