Austin is strongly devoted to his craft. He believes in the integrity of his work but also wants to impress Hollywood producers. He's often caught between his own needs and the needs of his father and brother. Though Austin has achieved material success and a career, time with his nomadic brother Lee makes him realize how disillusioned he is with his own city life. He and Lee are competitive and combative, but Austin seems to have a real desire to connect with his brother at several points in the play.
Lee is aggressive, brutal, controlling, and often physically violent. But he's also vulnerable and unhappy, expressing both contempt and desire/jealousy for Austin's life. Lee resents the assumption he lacks intelligence. When he has an opportunity to prove himself as a scriptwriter, he wants to improve his own situation and get his father out of poverty.
Saul expresses interest in Austin's script idea, but later drops it for an idea Lee proposes. Saul is seemingly friendly and diplomatic but primarily driven by profit motives.
Mom leaves for a vacation to Alaska and returns to find her house ravaged by Austin and Lee. She appears lonely and dissatisfied with her life and her warring sons.