One of the things that I’ve really enjoyed so far about this series is that with each book you get to see Dante and Japhrimel’s relationship evolve. All along Dante has treated Japhrimel like a human, no different from how she treats everyone else in her life. Dante seems to forget that Japhrimel is not a man but a demon and she receives a grim reminder of this fact.
Dante is also haunted by her past. Jace’s voice echoes through her mind, she sees his ghostly figure in a bar that he never visited in life, and once faced with a grown Eve all Dante can think about is her deceased friend and lover Doreen. It is a hard, hurtful past that she can’t put behind her, something that makes her more human despite the fact that she isn’t quite human anymore.
While you could pick this one up and enjoy it out of sequence with the rest of the novels I would recommend you start with Working for the Devil, the first book in the series. At this point there is just too much story, and while you would be able to pick it up along the way, wouldn’t you rather get to know Dante and Japhrimel from the beginning?