Wish granted but the pet started as a small one, then it grew slowly into a stronger one. As it grew stronger and stronger, it got angry at life. So one day it attempted Self Delete, it failed because it forgot it was immortal. Because of that, it got thrown into the nut house. Later, it got insane and grabbed one of the guards gun. The guard had imagination, so the wish stole it. So then the wish escaped, using the stolen imagination, HE TOOK OVER THE WORLD!
I wish someone killed that pet.