Percy and Francis Gun are the player characters and main protagonists in Gun Bros.
Percy and Francis are two superhuman soldiers and F.R.A.G.G.E.D.'s main field agents. They are both muscular, cigar-chewing men. Percy is a bald Caucasian man with a mustache and beard who wears a green bandanna and Francis is a bald African-American man. The official description for Gun Bros states that 'Percy and Francis Gun' are code names. It is likely that Percy and Francis aren't actual brothers, as suggested by their skin colors, unless the two are mixed twins.
In Gun Bros, the player will take control of one of the two and fight against T.O.O.L. soldiers and zombies on various planets. It is possible to have one bro controlled by the player and the other by AI, or to have both bros controlled by players via online multiplayer. Players can buy new armor and guns for the bros in the store.