Doctor Pascal

Doctor Pascal, also known as Pascal Rougon, is the protagonist and a selfless and dedicated medical doctor who turns his focus to research after twelve years of practicing medicine. Passionate about studying heredity, he utilizes experimental methods and uses his family as subjects for his investigations, much to his mother's dismay. He keeps meticulous records of his research, which are stored in files in his study. Doctor Pascal is not motivated by wealth or fame; his primary drive is the desire to provide healthcare to those who cannot afford it. Despite the family's efforts to destroy his work, he remains steadfast. His health falters under these pressures but is temporarily restored by a love affair with his niece, Clotilde. Tragically, he suffers a heart attack and dies, leaving his life's work vulnerable to destruction, which is carried out by his mother after his death.

Clotilde

Clotilde is Doctor Pascal's niece, sent to live with him after the death of her mother. Raised under Martine’s strict Christian tutelage, Clotilde initially aligns with Martine in her efforts to convert Pascal and destroy his research. However, as she matures, her feelings for Doctor Pascal deepen, and she realizes she loves him, ultimately becoming his mistress. Despite Dr. Ramond's proposal, her affection for Pascal prevails. After Pascal’s death, she bears his child, symbolizing the continuation of his legacy.

Martine

Martine is the steadfast housekeeper who has served Doctor Pascal for thirty years. She disapproves of his non-religious lifestyle and persistently tries to convert him to Christianity. Charged with raising Clotilde, Martine instills strong Christian values in her. Despite her devotion to Pascal, she ultimately supports Clotilde's religious convictions, which are at odds with Pascal's scientific endeavors.

Madame Rougon

Madame Rougon, or Félicité Rougon, is Doctor Pascal’s elderly mother. She disapproves of her son's lack of ambition for wealth and fame and is embarrassed by his unconventional research pursuits. Her primary concern is the potential scandal his work on heredity could cause if made public. Driven by this fear, she is determined to destroy his files and succeeds in doing so immediately after his death, erasing the tangible evidence of his life's work.

Doctor Ramond

Doctor Ramond is a close friend of Doctor Pascal and a suitor to Clotilde. Although he is genuinely in love with Clotilde and proposes marriage, he is ultimately unsuccessful as Clotilde's affections lie with Doctor Pascal. Despite his unrequited love, Dr. Ramond remains a supportive presence in their lives.

Maxime

Maxime is Clotilde's brother, known for his dissolute lifestyle, which contrasts sharply with Clotilde’s upbringing and values. His character serves to highlight the varied influences within the family and the complexity of hereditary traits Pascal seeks to understand.