Dr. Guillaume practices medicine as the local doctor in the French village where Sebastian lives with his adoptive family. He maintains a professional medical practice serving the villagers, though specific cases remain undefined. Romantically involved with Anne-Marie, Cecil's biological granddaughter who helps care for Sebastian, this relationship integrates him as a supportive figure within Sebastian's extended family environment. His presence primarily connects to these family dynamics rather than Sebastian's central journey to Spain alongside Belle. In English-language adaptations, the character is recognized as Dr. Phillips. Details regarding his personal background, family history, or character development across various media formats are unavailable.