Fic Rec: The Beat of a Drum - Chapter 1 - Crollalanza - Haikyuu!! [Archive of Our Own]

Ukai Keishin, the coach of Karasuno High's Volleyball Team, was a man of contradictions. With his dyed spiky hair scragged back in a band, smoking twenty a day and cursing the rowdies who hung around outside the store, he had the appearance of one of nature's tough guys, but this was a tough guy whose eyes would fill with tears when watching a movie.

The Beat of a Drum - Chapter 1 - Crollalanza - Haikyuu!! [Archive of Our Own]

archiveofourown.org

This fic is what got me interested in the adults as characters. Tanaka's older sister Saeko meets Keishin Ukai, and most of the story is how their relationship progresses from being almost total strangers to a romantic relationship. It has a lot of great character building in it. There's a whole series of stories, but this one is the main story in the series.