He speaks in a deep, monotone voice, rarely having emotion in his speech. Like his sister Cindy, he parodies the stereotypical rebellious teenage behavior, such as dropping out of high school two years ago (much to George's anger); this would make him at least 16 years old. He also has a tendency to be sarcastic and make observations about his family, in particular his father.
Peter was primarily used as a background character, but a long-running yet rarely seen gag implies that he is a cross-dresser, such as going to cheerleading practice (even wearing the outfit at the dinner table) and attending ballet class, wearing a tutu. His father is livid when he sees his son in a cheerleading outfit, but Virginia is more accepting, having been aware of it before George was.
Peter is a light blue wolf, with a darker blue nose. He typically wears a purple shirt that has "Ear Deth" on it. Additionally, he has dark blue sweatpants. When cross-dressing, Peter will wear his cheerleading or ballet outfit, both of which have pink as the primary color.
- His name is a reference to the musical story Peter and the Wolf.
- A salmon pink-colored version of Peter made a cameo in the Netflix film, Rocko's Modern Life: Static Cling among the background citizens watching the Fatheads reboot.