Walk A Mile (The Enemies Trilogy Book 2) - The Enemies Trilogy, #2

When a botched assassination attempt leaves Alex Manners stuck in the body of his arch-frenemy, he's forced to strike a truce until they find a fix to the problem. But the swap has unearthed latent memories, uncovering a villain who's been stalking Alex for years. Alex's only defense is the anonymity lent by a different face. If Alex wants his body back, he'll have to contend with a time-travelling pyrokinetic, a psychic orchestrating experiments on superheroes and a pair of vigilantes cutting a bloody swatch through the city.
More importantly, he'll have to confront the ever-looming specter of the Forgettable Man.