I have stories like that too. Ideas i’ve had but never been able to put them down on paper.
If I were writing it Id’ start with hunter showing up at the school. I”m presuming the teachers show up days/weeks before the term starts. He moves in and finds his way around. that;’s when it’s established that he’s a muggle. That some teachers accept him automatically, others not so much.
He’s half pitied, half detested. A normal ‘weak’ human. But an oddity because he doesn’t seem like a teacher. He’s confident, able to to take care of himself. some teachers can pick up on the sense of menace about him, it scares some, intrigues others. He has a attitude that they’re not always used to, a confidence that some aren’t used to.
He may also have a degree of disdain for magic that some pick up on. Maybe also a bit of mystery about him. Is he a squib? Where did he come from? How did he come to be at hogwarts?
when he teaches the kids there are issues. Why is he teaching them bout muggles and the muggle world?
To me it cn be just as much his relationship with the other teachers as students. He’s going to befriend someone or at least the relationships work to develop some mutual respect. they see him as more than a muggle, he realizes that magic isn’t just the easy way out.
Anyway, just thinking out loud.