Although she's only 35, Berniece has already been a widow for three years. After the death of her husband, Crawley, she brought her daughter to Pittsburgh, where she currently lives with her father's brother, Doaker Charles. She and her daughter, Maretha, occupy the upstairs rooms in his house, and the only real evidence of her presence on the first floor is the piano she brought with her from Mississippi; it's a family heirloom. Berniece's relationship with the piano is complicated. While her mother was alive, she played it regularly at her mother's request. Since her mother's death, though, she hasn't touched it. She feels it's haunted by the family's past. At the same time, she recognizes it might be a key to her daughter's future; Berniece has Maretha taking piano lessons and hopes she will someday become a piano teacher. The piano will secure Maretha's future. By clinging to the piano, Berniece clings to the family's tragic history of removal from Africa and enslavement in America; by refusing to play it, she refuses to claim that history as her own. At the end of the play, she realizes that only by reclaiming it can she come to grips with it and begin to move forward.
Boy Willie may be 30, but he's still a boy in many ways. He tends not to see beyond his own needs and desires, and he's full of talk, dreams, and schemes. His plan to sell watermelons in Pittsburgh is one of those schemes, but he also has a much bigger one. He believes he has found a way to stop sharecropping and become a farmer in his own right. There's farmland for sale back home in Sunflower County, and Willie plans to buy it. It's the very land his ancestors once farmed as enslaved workers. Unfortunately, to be able to buy the land, he has to sell the piano he and Berniece inherited from their mother. Boy Willie believes his sister is stuck in the past and he is moving forward, yet he is the one who insists on remaining in Mississippi and buying the land on which their family worked as slaves. He believes she sees their situation as irredeemable, but he is the one who refuses to bring children into a world in which he cannot provide for them.
Doaker Charles is the new patriarch of the Charles family. He's a 47-year-old railroad cook—a steady, well-paid, and respectable job. When not at work, Doaker is a mild homebody who tends to nurture anyone who turns up in his house; he's always ready with a meal, a glass of whiskey, or a story. But no matter how gently he does so, Doaker always tells people the truth as he sees it.
Lymon is just a year younger than his friend and current business partner Boy Willie. He's a quiet young man, but a very straightforward one. Although Lymon acquired the truck the two men arrive in, he has no intention of returning to Mississippi. He hopes to use his half of the proceeds from selling the watermelons to get started in Pittsburgh, where he hopes to find a girl and settle down. He's a lonely young man who proves susceptible to just about any young woman's charms.
When he arrived in Pittsburgh, 38-year-old Avery got a steady job as an elevator operator and is doing much better than he did in Mississippi. After having a portent-filled dream, Avery decided to become a preacher and is working hard to make that plan a reality. He has been talking to a bank about a loan so he can set up his own church and congregation. Berniece is a part of his plan; he considers her a good candidate for the job of preacher's wife.
From time to time, Wining Boy drifts through Pittsburgh. When he does, he stays with Doaker and Berniece—at least until Berniece asks him to contribute to the family's expenses. As Doaker's older brother, Wining Boy actually remembers even more of the family history back in Sunflower County than Doaker does. A traveling gambler and piano player, his experience of life is also very different from that of his staid younger brother. He has his own brand of wisdom to share.
Berniece is raising Maretha to be a self-confident young woman and does not want to weigh the girl down with her family's tragic past. Maretha is subjected to manipulation by her uncle Boy Willie. He tries to influence her to take up guitar because it's easier to learn than the piano. In fact he simply wants to steer her away from the piano so he can sell it.