Assistant to the Villain (Assistant and the Villain #1)

"With ailing family to support, Evie Sage's employment status isn't just important--it's vital. So when a mishap with Rennedawn's most infamous Villain results in a job offer, naturally she says yes. No job is perfect, of course, but even less so when you develop a teeny crush on your terrifying, temperamental, and undeniably hot boss. ... But just when she's getting used to severed heads suspended from the ceiling and the odd squish of an errant eyeball beneath her heel, Evie suspects this dungeon has a huge rat"--