The Darkangel Trilogy by Meredith Ann Pierce, Hardcover 1990 Guild America Books
 
Aeriel is kidnapped by the darkangel, a black-winged vampyre of astounding beauty and youth. In his castle keep, she serves his 13 wives, wraiths whose souls he stole. She must kill him before his next marriage and comes into full power, but is captivated by his magnificent beauty and inner spark of goodness. Will she choose to save humanity or his soul?
 
7.10