Re: battle.
Petunia was serious when she told Remus she wasn't leaving his side. She will have her knives and her guns and she asked for permission from exactly no people. She will fight wherever she ends up.
Quentin is with Team Fillory?? He's using some battle magic, but he's not rly suuuuper 100% with that. Still, he's doing what he can. He'll try to lead people to the right portals and stuff before this, though. He wants to make sure they get to places safely.
Cho Chang will be out doing defensive spells to protect those who are offensive in nature. She's trying to keep people from dying too much. This is the real life. She's trying not to think about the last time she was doing this because...yeah. Bad times. Still.
Finn is going wherever Rey goes. He doesn't have a weapon, but as soon as he can manage to get a weapon off someone, he will. He's basically pulling a Dean Thomas rn.
Annabeth Chase has her sword and her dagger and she's basically fighting everything and shouting out battle plans to anyone in the general area of where she is. She is able to adapt pretty well to whatever the fuck is happening.
Leo Valdez is supposed to be Tech, but wherever the demigods go, he goes. Plus, he has fire. He's only using it if no one is too close.
Cleo is team water people. She's using water to fight things as much as she can. And wind. sjdkanfd. Whatever she can. If she turns into a mermaid? Well, that happens. sdkjanf.
Bill is out to do all the things. Probably sticking close to his fam and stuff. IDK. Probably also trying to help people get to safety and protect the people.