Menos and his brother first appered in the Teen Titans TV show. They made their TV debut in "Titans East" (part 1 & 2). During the 1 year gap after the death of Superboy Mas Y Menos became members of the real comic book team.
Sam Register and Glen Murakami came up with the idea of the characters. Freddy Rodriguez voiced both brothers in the TV show. Media History
Titans East (part 1 & 2)