there's a subplot in the 'death of jean dewolff' story arc about peter and matt progressing from 'colleagues' to friends, and it starts with matt defending a bunch of young rascals who beat up one of the elderly residents of aunt may's halfway house.
right after this arraignment hearing, sin eater, the murderer of captain dewolff, shoots an old friend and mentor of matt's to his death, which makes this whole ordeal personal to daredevil, too.