Peter Puppy
Peter Puppy turns into a large monstrous dog whenever he is hurt or scared. This trait is very similar to that of Bruce Banner as the Hulk, or Dr. Jekyll and Mr. Hyde. While he is in this form, he will attack Earthworm Jim or anything that resembles him (as seen when he once attacked Psy-Crow, who had Jim's super suit on at the time). After a short while, he will change back to his natural form, unaided. The animated series expanded upon this, adding that tickling Peter would cause him to belch, then change back to normal.
In the Earthworm Jim video games, Peter has the ability to change into a large monster when threatened. He is from another planet on which Jim crash-landed after being sucked through a warp hole. Jim's Pocket Rocket was badly damaged in the crash, and Peter helped Jim escape the planet in exchange for being helped to safely return to his house. In Earthworm Jim 2, Jim chases Psy-Crow to Peter's planet following Psy-Crow's kidnapping of Princess What's-Her-Name. Psy-Crow has taken Peter's six hundred relatives hostage and is throwing them from the window of an abandoned air control tower. Jim must save the puppies by bouncing them to safety via a large marshmallow. However, should he drop too many puppies at once, Peter will "unleash" his wrath and severely damage Jim.
Peter's planet is battered daily by asteroid showers, raided by passing space dogs, and overrun with strange and dangerous octopus-like man-eating plants. His violent transformations may be seen as a defense mechanism to these constantly present dangers.
In Earthworm Jim 3D, Peter plays the role of Jim's Super Ego. This Peter is clearly based on the cartoon version.
The animated series changes Peter's origin considerably, portraying him as an ordinary dog. His appearance changed dramatically as well, with the artist giving Peter an unbuttoned teal shirt and black shorts as opposed to wearing no clothes. His fur was changed from purple/pink to white to make him look more like a real dog. A coward by nature, he was picked on by the other neighborhood dogs. One day Peter decided to prove his worth by performing the Taboo of the Dogs, attacking a running vacuum cleaner, something few dogs have attempted. His fear turns out to be well-justified as vacuums are canine-specific trans-dimensional portals. Peter is flung through time and space and eventually lands on the Planet Heck where Evil the Cat places a curse on him. The curse gives Peter human intelligence and his anthropomorphic form (and his nifty shirt) but also causes him to transform whenever he is hurt or scared. He eventually finds Jim and the two become good friends, with Peter serving as Jim's unofficial sidekick. As such, he had a much larger role in the cartoon series than in the games, appearing in almost every episode.
