GIR is a malfunctioning and dim-witted SIR (Standard-Issue Information Retrieval) Unit who is assigned to help Zim. However, GIR is often the reason Zim’s plans fail, especially if he’s after pizza or rubber piggies. GIR’s attempt to blend into human society seems to work since no one seems to think there’s anything bizarre about a green dog.
When the Almighty Tallest sent Invader Zim to Earth they did so to keep him from interrupting Operation Impending Doom II. However, Zim took his mission to Earth seriously. He enrolled himself in elementary school and tried to appear as humanlike as possible by wearing a pompadour wig and contact lenses. Yet somehow only one person questioned Zim’s green skin.
If there is one thing to say of Dib, it’s that he has determination. He’s obsessed with the paranormal and self-conscious about the size of his head. Wearing a trench coat and a hairstyle that likely requires a lot of pomade, Dib is extremely unpopular in school. But who has time for popularity when there is an alien to catch?