Sonny is a playable character in the arcade version of Double Dragon 3: The Rosetta Stone. He is the character to whom the third player is assigned when he chooses to play as a Lee brother, essentially being a palette swap of Billy and Jimmy with orange hair and a yellow version of their outfit. Since Sonny only exists to provide another Lee brother for the three-player mode (due to the game allowing multiple players to control the same character type), he has no official backstory and his relation to Billy and Jimmy - whether he's actually a third sibling or simply a fellow Sōsetsuken practitioner - is unclear.
Because the export version forced players to start the game off as a Lee brother and acquire the other character types through in-game item shops, Sonny serves as the default third player character in that version (as opposed to the Japanese version, which allowed players to start the game off as any character type). As a result, Sonny is shown prominently alongside Billy and Jimmy in the American flyer and cabinet art, which depict him wearing black pants and a yellow tank top instead of the actual outfit he wears in the game, making him stand out next to the other Lee brothers.
Sonny returned as an unlockable character in Double Dragon IV.
- Sonny is featured prominently in the artwork for Tiger Electronics' Double Dragon 3 LCD video game, which is reused from the arcade game's promotional flyer. Despite this, he is never actually mentioned in the manual, which instead mentions three of the four heroes from the NES version (Billy, Chin and Yagyu).
- In a prototype version of Double Dragon II: The Revenge for the arcades, Jimmy (Player 2) wore a yellow outfit much like the one Sonny wears. This was due to Jimmy originally sharing his palette data with Marian, who wears a yellow dress in the game.
- East Technology, the developers of Double Dragon 3, would reuse the name Sonny for another playable character in their beat-'em-up Silent Dragon.