The Demon Kiss by Juliana Haygert

A young woman with a secret heritage. A man who made a deal with the devil. And an academy where the students are just as dangerous as the demons …

Erin:
I’ve been kept from the truth all my life. Demons walk the earth, and I’m destined to slay them–I only wish I hadn’t lost someone I loved while discovering that truth.
Now the demons are after me. The only way to stay alive is to attend an academy for demon hunters–a school where I’ll learn how to kill supernaturals and slay the underworld’s minions. But I still feel there are secrets I’m not being told …

Rey
I sold my soul to save my family–and lost everything because of it. Now I’m a slave to the underworld, a fake hunter with half-demon blood.
I’ve been sent on a special assassination mission. If I fail, it means my life. But protecting Erin soon becomes more important than any other task, and there’s something about her that tells me her arrival at the academy will change everything …