Bitey first appears in the episode "Baby Steps", where Lana and Lisa were fighting for Bitey, because Lisa wanted to test her experiments on the rat, while Lana refused to let Lisa do so. Later on, Bitey, along with Lana, get trapped in a tree. Lana was trying to rescue Bitey, but her acrophobia (fear of heights) kicked in, and was too scared to get down. Clyde helped Lana and Bitey down the tree, causing Lana to hug Clyde in gratitude.
In "Fool's Paradise", Lana mentions him while praying before going to sleep.
Bitey is a standard rat, with gray fur, whiskers, buck teeth, and a pink tail.