Carnival of Souls by Melissa Marr
He stared up at her, the witch he'd thought he loved, and couldn't understand how he could've been so wrong. "You took everything from me"
"Not your life. I spared your life."
Marchosias flashed his teeth in a smile of sorts. "That's the price: your life if you fail."
So far this book is a little complicated but has some great plots and lines. It's taking me awhile to read but is good enough to keep me going. Definitely different from other books I've read.