At the heart of The Piano Lesson is a brother and sister couple at war over the question of using the family legacy. Berniece, the sister, fiercely protects the piano from being sold. She figures as the guardian of the family's past. Unlike other characters, the stage notes for Berniece are somewhat sparse, describing her as a thirty-five-year-old mother still mourning for her husband, Crawley. She blames her brother, Boy Willie, for her husband's death, remaining ever skeptical of his bravado and chiding him for his rebellious ways.

Berniece still constantly thinks about Crawley and has refused to re-marry. Though the play ultimately stages her seduction by Lymon—in some sense to recuperate her femininity—it is crucial that she figure as a woman-in-mourning. In this respect, she doubles as her mother, Mama Ola, a woman who, in her mourning for her husband, spent the rest of her days attending to the piano that cost him his life. Berniece will continually invoke her memory against her brother and his own appeals to his father, thus appearing as heir to a certain maternal legacy. Indeed, her mother led her to the piano in the first place.

Berniece played for her mother as a child, and served as priestess in the channeling of the family's ghosts, her music enabling her mother to speak with her dead father and animating its carved figures. The adult Berniece now leaves the piano untouched in an attempt to lay these spirits to rest. Moreover, she has refused to pass the piano's history onto her daughter and celebrate it within the family. Berniece can do nothing but carry the past and its traumas with her. In the final struggle between Willie and Sutter's ghost, Berniece will play the piano and resume her old role as priestess, calling the family's spirits to assist in the exorcism. Mystically, she will at once speak from the family's place of origin (Africa) and address the family's spirits from the present. Berniece thus assumes her duties as the link to the ancestors.