Like maybe the lead grew up in a different country which was war torn and becomes a child soldier then when they're 18-19 or whatever moves to a peaceful country and has to adapt to an ordinary student life with bullies who doesn't know better that the guy who they wanna bully is someone who has killed for breakfast, or someone who has experienced an extreme trauma but acts as if everything is fine and everyone thinks they're fine, but are shocked beyond belief when they find out what happened to them, or similar.