Billy was basically the ringleader when he and Fred were going through their bully phase, targeting Carlos and Rad relentlessly. Fred tagged along mostly—he wasn't really into it—but Billy drove the whole thing. He also had his eye on Alexis for a while and tried to make something happen there, though it never panned out. Honestly, his romantic ambitions and various schemes all got completely derailed anyway once the Transformers showed up and changed everything.
But Billy's story doesn't end with being a jerk. He and Fred eventually flipped and actually became genuinely close with Carlos and Rad, the guys they used to mess with. Carlos especially became someone Billy spent a ton of time around. It's one of those character arcs where the bullies find out they're not actually enemies with their targets—and maybe realize they have more in common than they thought.
Content compiled by AnimeList.moe from publicly available sources.
