Ooh, it reminds me of Marlys. Which is the name of a perfectly wretched person in a novel I cannot remember the name of. I think it's the hero's lame girlfriend in AS Byatt's Possession.

ETA: Blah! I remember what novel it's from. It's from a weird Teresa Medeiros medieval romance. It's an absolutely bizarre book. Marlys is the name of the hero's crazy sister who is a murderer, only no one knows it but her. There was also some weird sexual vibe between the sister and the heroine. I was kind of rooting for them to get together, because they had more chemistry than the hero and the heroine.