Luigi is Mario's slightly younger, taller fraternal twin brother and the deuteragonist of the Mario franchise. Throughout his life, he has lived in Mario's shadow, developing both cowardly and heroic tendencies. Despite this, Luigi has helped and fought alongside his brother on many occasions. Mario Bros. marks his first appearance in the Mario franchise and his debut in general. Originally an exact copy, then palette swap of Mario, Luigi was created to facilitate a second-player option.