|“||I'm tired of you bossing me around, Dad! All the running, all the studying, all the planning for your christian camp! I know you wanna break ground at 20/12, but it's not gonna happen! We can't get the permits!||„|
|~ Steve-arino's frustration|
He was an experiment to see what would happen if Steve was raised purely by Stan's parenting methods. While initially he was identical to Steve in every single way and becoming a model son in Stan's eyes, including being greatly athletic and intelligent, Stan's overly strict parenting caused Steve-arino to become resentful of Stan and his lack of freedom. These repressed feelings caused Steve-arino to become a sociopath who kills and eats cats.
He then used what he learned from Stan to fake his running away, kidnap Steve, and assume his identity. Eventually, Steve-arino was found out and decided to kill Steve to cement his status as Stan and Francine's only son.
After Francine opens the cages of the cats, the cats jump on Steve-arino and he falls out of a window. Thinking he is dead, the family begins to leave and is suddenly attacked by the clone. Steve-arino chases Steve around a propane tank which is shot by Stan and the resulting explosion sends Steve-arino flying into a brick wall.
The barely alive clone sees a gun and also sees Simon the cat. The two, determined to kill each other try to beat each other to the gun. Simon eventually grabs it first and a shot is heard, presumably killing Steve-arino. The clone's final words are, "I'll see you in hell."