Jimmy Leong was a resident of New York's Chinatown. He helped Vigilante/Greg Sanders in an early case and was adopted by him. Jimmy was proficient in several martial arts, including Judo and aikido. He taught Vigilante basic martial arms. They later both joined the Seven Soldiers of Victory. Jimmy found a friend in Wing who was also Chinese-American.
According to his retconned history, Jimmy entered adulthood and fell for a young porn actress. He was trying to help her when killed by Bugsy Siegel. The Vigilante took revenge for his death and adopted Victor Leong, younger brother of Jimmy.
Victor was introduced in "Stars and S.T.R.I.P.E.S" #9 (April, 2000). He time traveled with his mentor from 1949 to the Old West where they carved their own legend. Returning to the present, Vigilante retired and Victor sought a higher education. He is currently the owner of a restaurant chain and administers the rights of Sanders' old films.
A version of Stuff appeared in the 1947 movie serial The Vigilante: Fighting Hero of the Old West. He was played by George Offerman Jr. However, he was neither Asian nor a kid but rather an adult Caucasian man.