In most ways, Joe Keller is the protagonist in Arthur Miller's play All My Sons. It is his past actions and story that primarily drive the plot of this play. In fact, much of the plot of All My Sons centers on Joe's personal transformation as he goes from denying his greater responsibilities to society to finally accepting them. He is the first character to take the stage, and it is his suicide that provides the story's ultimate resolution.
Chris Keller, Joe's son, can be seen as a protagonist in this play as well. While Joe's plot-driving actions happened primarily in the past, Chris takes a more current and active role as the play progresses. His romance with Ann and their desire to get married drives the plot toward its climax and eventual conclusion.
Like his father, Chris experiences his own transformation throughout the course of the story. At first, he stubbornly clings to the notion that his father is not at fault in the deaths of the pilots as a result of the corners Joe cut in his factory during the war. Yet, by the story's end, he recognizes his father's complicity, confronts his own cowardice, and works up the courage to confront his father.