Souls Trilogy by Harley Laroux.
Leon I earned my reputation among magicians for a reason: one wrong move and you're dead. Killer, they called me, and killing is what I'm best at. Except her. The one I was supposed to take, the one I should have killed - I didn't. The cult that once controlled me wants her, and I'm not about to lose my new toy to them.
Rae I've always believed in the supernatural. Hunting for ghosts is my passion, but summoning a demon was never part of the plan. Monsters are roaming the woods, and something ancient - something evil - is waking up and calling my name. I don't know who I can trust, or how deep this darkness goes. All I know is my one shot at survival is the demon stalking me, and he doesn't just want my body - he wants my soul.
Her Soul to Take is book 1 in the Souls Trilogy. Each book within the Souls Trilogy is interconnected, following a different couple through a similar timeline in the fictional world of Abelaum.