Berniece's brash, impulsive, and fast-talking brother, the thirty-year-old Boy Willie introduces the central conflict of the play. Coming from Mississippi, he plans to sell the family piano and buy the land his ancestors once worked as slaves. His impulse is to use the family's legacy practically—that is, convert it into capital. In this sense, Willie will appear guilty of a denial or turn away from his family's traumatic past.

Willie approaches everything with a certain boyish and occasionally crude bravado. He is especially vehement on questions of race. Declaring himself the equal of the white man, he continually refuses to accept the racial situation that he imagines the others accommodate themselves to. Thus he insists that he lives at the "top" rather than the "bottom" of life and remains intent on leaving his mark on the world. Aware of the fear he arouses in whites, he knows that he wields the "power of death"—that is, the power both to risk one's life and kill if necessary—that ostensibly equalizes all men. Though the white man may wield the legal and political authority to punish him, he will only follow laws that he considers just.

Willie seeks Sutter's land as a means of standing shoulder-to-shoulder with the white man. Moreover, in a play intimately concerned with memory and inheritance, he imagines this purchase in terms of a certain paternal legacy. By selling the piano, he avenges his equally brash and impetuous father, Boy Charles, who spent his life property-less, doing as he might have done. The mark he would leave on the world memorializes the father. Similarly, he proposes that the family should consider the day that Boy Charles stole the piano their own holiday and their own Day of Independence. In light of this legacy, it is also not for nothing that Willie's namesake is his grandfather, Willie Boy, the slave who transgresses white authority, the carving of the piano, and leaves a literal "mark" on the world that sets the story in motion. In the final scene, Boy Willie comes to incarnate these paternal ancestors, engaging in a battle with Sutter's ghost that allegorizes the struggle between white and black across the generations. Though Berniece's call to the ancestors will lead him to understand the importance of the piano, he in a sense he already lives in the memory of his ancestral legacy.