Deviant-Hunter: Blood Oath - Eve of Light: Deviant-Hunter, #1

Frank Sanders knows all about going to extremes to ensure certain ideals. As a one-time Black Peacemaker for the Heartland Security Agency, the government taught him a variety of unsavory methods to preserve the sanctity of American families and protect their children against domestic threats. He learned a little too well. Designated as too extreme for even a black-ops unit, Sanders was forced to retire.
Some retirees choose to spend their time fishing. Some busy themselves with house and garden projects. Sanders chooses to hunt. His targets: viral humans infested with parasites that feed on blood and light, endowing their carriers with supernatural abilities. Remaining in the shadows and free of constraints, Sanders has excelled at locating and eradicating those he calls deviants. But when the government asks him to track down another notorious Black Peacemaker, who's not only been infected with the bizarre virus but has given it to his wife and children, Sanders sets out on his most difficult hunt to date, one that will force him to question many of the ideals for which he's fought and push him to extremes he's never known.
A gritty, surreal, and uncompromising Dark Metaphysical Fantasy.