That girl doesn't have a screw loose, she has an entire box of screws dropped on the floor and rolling under the workbench.
Between whatever weirdness is with her family and the scumbag teacher she is well and truly fucked in the head. She's probably not unfixable but jackass McGee over there ain't gonna be the one to do it.
I've said it before, I have no idea where the author is going with this clusterfuck but I'll be gods damned if I'm not all in on seeing how deep this messed up rabbit hole goes.