"Viper" is the alias of "Jerome", an African-American boy, and one of Billy and Mandy's fellow elementary school students. In the school, Jerome has the social status of a nerd.
In his debut episode, Jerome is a member of the Secret Snake Club; in the Secret Snake Club, Jerome's codename is 'Viper'. Along with his fellow 'snake nerds'--'Wiggly' and 'King Cobra'--'Viper' seeks the destruction of all the cool kids in the school, as the none of them are cool. To achieve this, they seek to summon "Shnissugah", a supposed patron and protector of Nerds just like themselves.