Sex & the Immortal Bad Boy by Stephanie Rowe
Immortally Sexy #4
Paige Darlington has a problem. See, she's the former apprentice to Satan's right hand, Becka Gibbs. As a result, she's got this pretty much all consuming need to be bad... not her fault, right? Well, that will be a small comfort when she loses all human emotions, including the ability to love and care about those who matter to her.
To keep his brother alive, Jed Buchanan works for Satan Jr., the heir to hell and the most evil being in existence. Jed has been forced to do a lot of unsavory things during his time on the "job" and his latest assignment - killing Becka Gibbs - isn't pleasant either. It only gets more complicated when he arrives at Becka's apartment, and inadvertently attacks Paige, a beautiful, sexy demon who decides that saving his black soul will be just the thing to keep her own from rotting.
But can the Devil's minion and the Devil's assassin possibly find true love?