Red Oni, Blue Oni: Blue oni in the animated series, red oni in the comicbook and film.Jack-of-All-Stats: In the Super NES game, where his fighting style focuses more on flexibility.His role is also bigger than Jimmy's in most adaptations. The Hero: He is the Player 1 character and Marian's official boyfriend, two facts that combined give him a bit more of protagonism than Jimmy.Color-Coded Multiplayer: Billy is blue (except in the second arcade game, where he wore black).This also occurs in the actual arcade game if both brothers defeat Willy together. Cain and Abel: Abel to Jimmy's Cain in the first NES game.
Early concept/promotional art for the original game depicts Billy not only as the darker haired brother, but has him wearing the red outfit instead of blue, which implies that he might been originally intended to be the Player 2 character (before the identities of the Lee brothers were fully established).
Adaptation Dye-Job: Blond in the arcade games and Neon, brown hair in both the NES and PC Engine games, and black hair in the animated series.
Sousetsuken is a fighting style that combines the techniques from all sorts of martial arts such as Karate, Shorinji Kempo and Tai Chi into one school. He began his Chinese martial arts training at the age of 12 and went on to master several fighting styles until becoming the Sousetsuken successor at the age of 20. Successor to the Chinese martial art of Sousetsuken. Voiced in English by: Michael Donovan (Animated series), Jeff Luke ( Neon), Dan Avidan ( River City Girls)The de facto protagonist of the Double Dragon series.