OK I know how strange this might sound but hear me out.
Ben= James Potter. He's seen as a hero throughout the entire series even though he can be a royal jackass and a child.
Gwen= Lilly Evans. Very studious and talented as well as kind and compassionate.
Kevin~ Severus Snape. Has lived a very hard and abusive lifetime and still carries a lot of open wounds. Is connected to the underground and is willing to go into the moral no-man's-land to do what is right or get the job done.
Grandpa Max~ Dumbledor. The wizened elder with more than a few skeletons in his closet, seems to have the answer to everything and is seen as an all-powerful guide but as the story progresses he eventually becomes much more human.
Am I the only one who sees this?