Heroes is the plural form of hero, denoting more than one. Example: There were many heroes during Nine-Eleven. Hero's is a possessive form denoting something that belongs to the hero. Example: The...
It could either be considered Jason Grace or Percy Jackson. Jason is lost, figuring that he lost his memory, and doesn't know where he came from. However, at the end of the story they realize that...
I am not sure what story you are thinking of, but Hero in Much Ado About Nothing is not much of a hero. In fact, she'd be a heroine if she were heroic, which she isn't. She's a bit of a doormat...