Gir is silly and dumb he’s only 11 years old and Zim is 1000m years old 
Zim is smart but he can sometimes be dumb his most hated enemy is enemy is named Dib he has a sister named Gaz who is always playing her video game console she’s mean and rude she doesn’t like Dib she thinks he’s crazy Dib is a human unlike Zim He’s a alien who is rude but sometimes caring for Gir is a robot that sometimes wears a green doggie costume Zim has a human disguise Gaz is also a human Dib doesn’t like Zim.