Something where Foggy is blinded, temporarily or otherwise, (my preference would be for temporary but with him not actually knowing that til it comes back, but writer's choice) and he is obviously absolutely terrified but is pretending to be okay becuase he doesn't want to imply that there is anything wrong with having a disability because he thinks that would be insulting to Matt. Like if he shows how freaked out he is, that implies that he pities Matt or something equally ridiculous. And Matt obviously knows what's really in his head, not only because of his abilities but because he has been through this himself and Foggy has every right to feel what he is feeling. So this might lead to Matt feeling guilty because for a start he knows he's a lot better off than the average blind person and also because he feels like he is getting in thr way of Foggy dealing with this in the way he should.

Basically a whole lot of angst, a large dollop of friendship and slash if that's your preference.