Iridescent — Carol Oates

Candra dreamed of saving the world one person at a time. She never expected to become an angelic weapon and the last hope in a battle against ultimate darkness. Falling for a Nephilim wasn't part of Sebastian's plan. Distraction is something he can't afford when his rival, Draven, wants what Sebastian has. Lies, manipulation, and corruption are twisting the lives of the citizens of Acheron. The Arch is missing from heaven, and a demon is intent on claiming the city. At a time they should be growing closer, grief and paranoia are driving Candra and Sebastian apart. Soon, Candra must face a terrible choice. If the price of restoring heaven is a human soul, who deserves to be saved?