Foggy used to have an abusive boyfriend/girlfriend. It started off with little things, losing their temper, being secretive and getting angry when Foggy brought it up, and ended with at least one instance of physical violence. And it's years ago now, and Foggy got out of it. He doesn't even really think about it.
One day, Matt does something (loses his temper, punches a wall, gets mad at Foggy for bothering him about the Daredevil thing) and suddenly Foggy's right back where he was when he was younger. Scared of someone he thought wouldn't hurt him, that he could trust not to hurt him (even though he knows Matt would never touch him, he can't convince his brain of that).
Matt is horrified, not only to learn that this happened in the first place (he didn't know, OR for more angst, it happened while they were at college and Matt beats himself up because how could he have missed something like that) but also that his actions have made Foggy frightened of him
Gen or slash - Matt's temper
One day, Matt does something (loses his temper, punches a wall, gets mad at Foggy for bothering him about the Daredevil thing) and suddenly Foggy's right back where he was when he was younger. Scared of someone he thought wouldn't hurt him, that he could trust not to hurt him (even though he knows Matt would never touch him, he can't convince his brain of that).
Matt is horrified, not only to learn that this happened in the first place (he didn't know, OR for more angst, it happened while they were at college and Matt beats himself up because how could he have missed something like that) but also that his actions have made Foggy frightened of him