Chromatophobia by W.D. County

His orders: defend a team of civilians from an enemy he cannot see.

Sgt. Miles Reardon has the sharpest vision of anyone alive, although it comes at a price: he sees only shades of gray. He grew up being taunted, embarrassed, and blamed for mistakes where color was a factor. He buried his feelings in order to survive, and eventually found the perfect job as sniper.

That changes when a man in Antarctica becomes infected by a colored rash that shifts in unusual patterns. It spreads by absorbing color from its environment, leaving its surroundings as gray as a black-and-white photograph. As the rash grows, it bestows extraordinary and dangerous abilities on the man. The US government moves him to a colorless isolation vault in a secure biohazard facility and assembles a diverse team to study him.
Miles gets the task of keeping them safe.

Category: Science Fiction – Military