Autumnavenger
"If you really want to be hero that badly, there might actually be another way. Just pray you'll be born with a quirk in your next life, and take a swan dive off the roof of the building." Katsuki didn't know why he said it, but he never imagined Deku would do it. So now that he's standing behind Deku on the roof of his school, he doesn't quite know what to do. There are too many confusing emotions when it comes to Deku that he doesn't know how to navigate.
Or when Izuku decides to attempt actually taking his own life, and Katsuki has to clean up the monumental mess he made. And ends up coming face to face with a few more emotional breakthroughs than he's ready for.