Mathilda
The novella is told from a point of view of a young woman called Mathilda, who expresses her desire to tell her story to her friend, realizing that she doesn't have much longer left to live. Her mother died soon after her birth, and she was raised by her aunt. The main point of Mathilda's story is the incestuous confession to her by her father soon after he gets back into her life.
Mathilda's father
Mathilda's father could be seen as the main antagonist of the novella, whose incestuous confession and suicide soon after, changed Mathilda's life and led her to her isolation and tragic fate.
Woodville
Mathilda addresses her story to her friend Woodville to explain her sadness, and lessen the burden on her soul as she is nearing her death. Woodville even prevented her from committing suicide before he had to leave his estate.