Succubus Blues, by Richelle Mead

Georgina Kincaid has been a succubus for centuries, feeding off the life force of mortals through sex, and she’s kind of over it. These days she limits her feeding sources to the morally dubious, which is not as satisfying but squares better with her conscience than literally sucking the life out of good people. She works in a Seattle bookshop and counts humans among her friends as well as like-minded fellow immortals - vampires, imps, angels and demons. Life gets very complicated when her favourite author comes to town and a violent crime wave sweeps immortal ranks. Georgina can’t resist investigating the crimes and she is having trouble resisting the charms of the author, despite the potential perils. Mead employs a tongue in cheek style familiar from her Vampire Diaries series, but this succubus story is funnier and sexier.