I'm not sure exactly as I haven't read it. But generally, a graphic novel can be about various things like adventure, relationships, or a coming - of - age story. Maybe it's about a character's most important or 'golden' hour in their life.
I don't know as I haven't read it. But usually, the main characters are the ones who drive the story forward, so they could be heroes, villains, or ordinary people caught up in extraordinary situations.