The devil inside - Jenna Black (Morgan Kingsley series #1)

Possession. Murder. Mayhem. Let the games begin...

Morgan Kingsley is an exorcist who precariously walks that fine line between heaven and hell. She lives in a world in which demons co-exist with humans. Normally hailed as heroes, these demons can heal, help, and make strong the willing hosts who gladly accept their corporeal  possession... unless a demon steps outside the boundaries of the law. That's where Morgan comes in. She is an expert at making rogue demons leave their unwilling hosts.

But now the unthinkable has happened: Morgan's got a demon of her very own sharing - possibly overtaking - her body. But this sexy beast is so enticing that he may tempt Morgan to re-evaluate her prejudice against demons - if he doesn't get her killed first. For a war is brewing in the demon realm, and Morgan has just been forced to take sides...