Hunted By Darkness by Brianna West

In the final book of this duology, Nika might be forced to choose between love and the end of the world…

Nika
I’ve got the voices of several dead in my head. I’m a Soul Collector, and I’m being hunted by a demon with my gorgeous boyfriend’s face. Weird doesn’t cover the feeling. If I don’t send the demon back to the After, he’ll destroy the world, so I’m learning everything I can about who I am and what my power is capable of doing. But fate works in strange ways. Suddenly it’s not just Silas, my best friend, Lev, and I fighting to stop the demon. I now have three extra men bent on helping me save the world. Except, the jealousy and tension between my overprotective mercenary and them threatens to ruin everything.

Silas
As an infamous and unkillable assassin, it’s a rare day when someone gets one over on me—but I’m dealing with an opponent only my feisty rebel can fight. She’s determined to save the world, and I’m determined to keep her safe no matter what it takes, no matter who I have to kill. I’ve made it my business to destroy any bastard who’s ever hurt her, or who ever intends to, but the three I can’t are the worst yet. My goddess is too kind, and she welcomes the undeserving lot with open arms. They used to be the enemy, and now they say they’ll do whatever it takes to protect her. What a load of bollocks.