SPOILER: heres Andrew's Rival in the main universe, John! In the main universe Andrew and John are following the path of Andrew's Ancestors, they stay constant rivals, and it turns out in order to not get into a fight and destroy the universe, they release their anger, and it has spread across all of time(eventually reaching Andrew and latching onto his rival, after that their rivalry made Andrew and Johns Mirror all the rests(Naruto and Sasuke, Goku and Vegeta, Saitama and Sonic etc.) eventually leading them to have to carry on the fight that never happened, Andrew and John go to all the mirrors and learn from them, and go throughout all of the multiverse and time to gain help and power, to finally settle things.
