Paul's wife and a fellow medical professional, who becomes a key support figure during his illness, and writes the Epilogue reflecting on Paul's life and work.

An oncologist recognized for her expertise and compassionate bedside manner, who plays an essential role in guiding Paul through his medical journey, balancing her responsibilities as both a doctor and a colleague.

Paul's fellow resident at the hospital, with whom he shares a close bond during their training, facing the pressures of medical life together.

The head of the neuroscience lab where Paul works, admired by Paul for his dedication to science over fame, offering him mentorship and insights into the challenges of a dual role as doctor and patient.

The young daughter of Paul and Lucy, whose birth brings joy and meaning to the family during a challenging time.

Paul's father, a dedicated doctor whose professional commitment, and later support during Paul's illness, is a significant influence on Paul’s life and career.

Paul's mother, who fosters his early love for literature and plays an active role in supporting him through his education and illness.