Ruth was Élise de la Serre's nursemaid and servant of the de la Serre family.
Oblivious to the fact that the de la Serre family were Templars, Ruth often wondered why the young Élise preferred playing with the boys and toy soldiers to the girls and their dolls. When Élise was six years old, Ruth and the de la Serres attended their neighbor's birthday party, where the young girl chose to play with boys rather than those of her gender. Ruth hastily dragged her away, aware of the other nursemaids' disapproving stares, and told her to play with dolls.
Concerned for her well-being, Ruth often fussed over Élise, which only resulted in irritating the child. She always hoped that Élise would settle down to girlhood and take interest in things considered appropriate for her gender. Unfortunately for Ruth, her dreams were crushed with the arrival of Arno Dorian.
Ruth became Élise's confidant when the latter's mother Julie had fallen ill; every morning, the young girl asked if her mother was "awake", meaning "alive". When Julie died, Ruth worried for Élise and her father François, and tried to ease the young girl's pain by embracing her and telling her to let it go, which Élise respectively refused.
When Élise left to study in the Maison Royale de Saint-Louis school at Saint-Cyr, Ruth remained at the de la Serre household and served as a maid.