The Siren's Demon — E.A. Reynolds

Darik loves the idea of a demon in his bed and when the chance arises his primary goal is to seduce and claim Trinity as his own. However, Trinity's ex has plans to win him back and this puts Trinity between two sirens, each determined to have him. Trinity is only half demon but everything about him is incubus, especially the dark half that will do anything to keep his mate from leaving him. Trinity doesn't want to expose Darik to this and resists his advances at every turn until he can't fight anymore. Then he lets his hunger for Darik take him over. As Trinity falls for Darik, Trinity's ex launches an attack designed to destroy the demon and his lover because, if he can't have Trinity, no one can. However, Darik isn't the powerless human he appears to be and won't give up his demon without a fight.