Retribution (The Dark-Hunter World) by Sherrilyn Kenyon

William Jessup Brady navigates a treacherous world where the line between good and evil blurs. As a gunslinger with a reputation for his merciless ways, he finds himself caught in a deadly game that could cost him not only his life but also his very soul. Haunted by his past and measures of revenge, he discovers that every choice he makes has a ripple effect.

When his path crosses with an unexpected ally, he learns that there’s more at stake than just his own survival. With emotions running high and the stakes at their peak, William must confront the darker aspects of his existence and decide what kind of man he truly wants to be.