It is hard to put Martin McDonagh's The Banshees of Inisherin into a genre box or give a simple explanation of what it is about. It has comedic elements but also dark drama. It is a strong character study.
There are plenty of themes than an audience can take from it. And plenty of dramatic things happen.
Plenty of the plot and action centres around the two lead characters, Pádraic and Colm (played by Farrell and Gleeson).
But the secondary character, Dominic (played by Barry Keoghan) has a notable role. He is a friend of the lead pair and incites at least some of their sparring. He is the son of the island's policeman. But he is abused by his father in more than one way. First he steals some of his fathers alcohol and gets a beating for that. When the fact of the beating is reported by Pádraic to other islanders, he incurs a beating from the policeman who further punishes his son as well. In a later drunken rant, Pádraic also accuses the father of "fiddling" with his son (without, apparently, having been told by Dominic) But this appears to be true.
Later we see some of Dominic's despair that he can't attract any of the women on the island to pay attention to him, partially because he is regarded as a fool (though we also see hints that his he is far cleverer than his public persona makes him appear).
Close to the end of the movie, he dies by drowning in the local lake. But we don't have any hints as to why or how.
Was he murdered to avoid further shaming his father? Did he commit suicide from despair? What point is the audience supposed to draw from his death?