Severed - Sarah Alderson

Fate brought them together. Now it's threatening to tear them apart. As the last in a long line of demon slayers, Evie's destiny is to end the war that has raged for centuries between humans and demons. Lucas, the half-human, half-Shadow Warrior who was sent to kill her, has betrayed his own Brotherhood and his family to fight alongside her. With an army of unhumans on their tail, Evie and Lucas are forced into an uneasy alliance with a group of rogue Hunters who offer protection and the promise of answers. As the past is untangled and the dark history of the Hunters revealed, Evie discovers that severing the realms is going to require a lot more than just fighting. It's going to require a sacrifice - one that only she can make. ...More than realms will be severed.