Jeanne is the youngest daughter of Duchess Danton and the younger biological sister of Catherine. After her mother married Duke Foyer, Jeanne became the stepsister of his daughter, Cinderella. The family lived together with the Duke and Cinderella before the series began.

Physically, Jeanne is a young woman of average height with medium-length brown hair, usually worn in low pigtails. A notable characteristic is her slightly heavier build compared to peers, a consequence of her constant eating. This frequent snacking often necessitates alterations to her dresses to accommodate her expanding waistline.

Personality-wise, Jeanne initially displays spoiled, vain, and mean-spirited tendencies, particularly towards Cinderella, mirroring her mother and sister. She actively participates in making Cinderella's life difficult, assigning her chores and showing ingratitude, even when Cinderella saves her life. Her strong ambition drives a desire to marry Prince Charles and become the next princess of the Emerald Kingdom, viewing other young women as rivals.

However, Jeanne also demonstrates a capacity for kindness and consideration distinct from her relatives. She trembles during thunderstorms and when hearing scary stories. Despite frequent arguments with her older sister Catherine, she maintains an underlying love for her. Her relationship with Cinderella evolves significantly: beginning with cruelty and demands, she shows sporadic concern, such as worrying Cinderella's outdated dress might cause embarrassment at the royal ball.

A pivotal shift occurs after Cinderella is revealed as Prince Charles's chosen bride. Jeanne's attitude transforms from antagonism to genuine kindness and affection towards her stepsister, marking a permanent reconciliation unlike earlier fleeting remorse. Her initial interactions with Prince Charles, based on ambition, involved treating him dismissively when he was disguised as a commoner, assigning him chores. The depth of her feelings for him beyond seeking status remains ambiguous.

Within the household, Jeanne contributes to Cinderella's mistreatment under the stepmother's direction. Her noted traits include clumsiness and an inability to dance properly. Her large appetite remains a consistent element, often leading to frustration if her eating is restricted.