Poison Tongue by Nash Summers

Levi Bell can see a person’s soul just by looking into their eyes. In Monroe Poirier’s eyes, he sees the devil himself.
When Monroe moves back to the small Southern town of Malcome, Levi is repelled by the darkness of the stranger’s soul. But Levi is cursed to love things dark and wicked, and he’s seduced each time he looks into Monroe’s eyes—and drawn to the swamp behind the old Poirier house.
As strange occurrences begin to happen when shadows and visions visit him in the night, Levi sees a flicker of something good in Monroe’s soul. But the need to submerge himself in the swamp’s murky waters grows stronger as Levi’s desire for Monroe becomes unbearable.
In his struggles to help Monroe save his soul, Levi will have to decide if it’s worth losing his own.