Enthralled

Edythe Grey is immortal. She's been around for over one hundred years. She decided a long time ago that she wouldn't hunt innocents. So she's become the Avenging Angel, a serial killer who targets rapists and murderers. She spends her nights at bars and clubs, keeping her ears and eyes open for new targets.
Lily Reed is a college student. She's spending the night out with her friends when she's approached by an older man. She blows him off and he follows her after she leaves.
Lily's life is saved by this mysterious woman. She doesn't know who she is, but she knows she has to meet her. Edythe becomes strangely attached to one of the girls she saved. She decides to break one of her biggest rules to meet this girl again.