Succubus Blues by Richelle Mead

Mead has created an intriguing character with Georgina Kincaid, succubus. As an immortal creature who absorbs the sexual energy from her "victims", portraying her as a shy and insecure bookstore clerk creates a delicious twist in the story. She also seems to have a conscience, and prefers to only feed off of scumbags, leaving the nice guys of the world alone.

But events force her...hand. Another one of Mead's usual love triangles develops quickly when she first encounters her favorite author, Seth Mortenson, at a book signing at Emerald City bookstore, where she works, and makes an utter fool of herself, then when she meets a mysterious and handsome stranger, Roman, who definitely makes her resolve not to involve nice guys in succubus business...hard to stick to.

For the squeamish, there are two extremely explicit sex scenes in this book, so handle with care.

Like many urban fantasy novels, this is set up as a little bit of a mystery. One of the lesser immortals, a vampire, is killed. Their toughness is legendary, and the only mortals able to do the deed are born vampire slayers, there's either one of those hanging about, or perhaps, as Georgina finds out when she begins to play amateur detective, he has been killed by another immortal. The attacks on immortals continue, and Georgina continues to investigate, even when the arch demon of Seattle tells her to butt out.

While dancing the tango with the two men in her life, Georgina must figure out the puzzle before any more of her fellow immortal friends get killed.

There's some interesting flashbacks to her mortal life, before she made a deal with a demon to become a succubus.

Mead has created an interesting and conflicted heroine, as required, and given her some moral - really, a demon has morals and scruples? - dilemmas to overcome. The whole demonic realm appears to run almost more like a business organization, with quotas for the number of souls corrupted, etc., than like anything remotely theological. A fun concept. We'll have to see where Mead takes it.