Reaper’s Fire by Katherine Bogle

Collecting souls for a Reaper should be easy, right?
Wrong.
Two weeks ago, I learned supernaturals were real. And surprise!—I’m one too. Unfortunately, the movies got it wrong: I have no quirky teacher to help me combat my new hunger, or a fairy godmother to sweep me away from all of my problems. Instead, a vicious demon queen calls herself my master, and even my hot new vampire friend can’t keep her at bay.
Being a Reaper might have sounded cool once, but it turns out killing people isn’t so simple, especially when a manipulative Princess of Hell is forcing you to do it.
If I refuse her majesty, she’ll kill everyone I hold dear.
If I don’t? I might lose my soul to the Devil.