All the original villains from fairy tails, like the big bad wolf, the evil step mothers, the evil queens and kings, the first witches etc they started the school not long after their story 'ended' The heroes thinking they'd been defeated and the stories would believe one to think so. Not just four founders but a fair few. How about instead of heads of houses we have Subject heads? Like one head for witchcraft but more like three to four witches teaching different aspects of witchcraft? The head of science and a few science teachers, Frankenstein for Biology, Jekyll & Hyde for chemistry and so on?