Darkest Angel by Gena Showalter
I only read the Gena Showalter & loved it, an Angel and Harpy pairing awesome. Bianca is Gwen's sister and a true Harpy. Lysander is an Angel who finds out she is his temptation so thinks he will make her into him so takes her to his cloud where she drives him batty, until he sees he was wrong to take away free will from her. I loved it that the hero was a virgin, a stranger to desire and even kissing. Both of them try to reform the other. Bianca realizes he is her consort and is willing to put up with the humiliation that will come when she introduces him to her family, but he isn't. I loved it when she said she wasn't willing to be a secret and she only stole from the wicked. A pretty good book about opposites plus we get so see Gwen and Sabin marry.