I’ve been trying to remember the details on this one for years, and can’t pull enough out to find it.
It’s a young adult book I read several times growing up, always taking it out of the library. It was stocked in the first shelf of the Young Adult section, which means the author was somewhere between A and maybe N, I think.
The cover had, in the top left corner, a boy standing on the edge of the school roof, with wings or a parachute or contraption of some kind. Down below were two boys looking up at him, possibly waving their arms or shouting at him not to jump.
The boy on the school roof wasn’t one of the main characters, though, just an oddball who was part of the local color of the school. The main character had just arrived at a very odd boarding(?) school, where many of the kids were quirky. I believe he found someone kind of normal already there to take him under his wing.
That’s all I remember.