Interesting idea, it's true really. Sure Snape was strict and even kind of mean but I think he could've been way worse. Even with Harry he could've been way worse to him than he was. I've always thought of Snape as the teacher you hate at the time because they're so strict and even mean but as you get older, you begin to appreciate and respect them. Umbridge was far worse, especially Harry (she made the boy write on his hand, it even left a scar.) Snape even brewed a potion to help keep Lupin from turning into deadly werewolf every full moon; he hated the man and yet he helped him.
I love the triptych style--that is so original! The first panel nearly moved me to tears. I've worked with kids who had similar upbringings and you're right--Snape could have easily become a heartless, amoral villain. Instead he was good, brave and honorable, even if most people could not see through his demeanor and recognize that. Beautiful job!