In this AU, Betrayus actually won the Pac World Wars all those years ago and took over Pac World in the process. In the midst of that, he adopted and raised little Pac as his son after he didn't have it in him to destroy the infant. This version of Pac of course grows up to be, well, a literal Pac Brat. Spoiled, aggressive, and whiny, he's pretty much a mini Betrayus and is unfortunately the heir to the throne of Pac World. He's loathed by all except his dad.

This AU is known as Twisted Fate, and it has an official (finished) fic for it here:
https://archiveofourown.org/works/40746660/chapters/102099852