Claudette Vance, the illegitimate eldest daughter of Count Vance, is excluded from the family's direct succession, placed behind her sisters Leina and Elina in inheritance. Her plebeian mother died young, and her father raised her as a servant rather than a daughter, shaping her emotionally reserved, disciplined, and typically taciturn and unsociable nature. She struggles to express feelings but harbors deep concern for her sisters, especially Elina. Despite inner conflicts, she commands widespread respect across the Continent for her integrity and righteousness, earning fierce loyalty from soldiers and commoners. Her military prowess and exceptional swordsmanship, amplified by her lightning-manipulating magic sword Thunderclap, forge her reputation as the "Lord of Thundercloud." This role often stations her at the volatile frontiers of the Queen's territory, executing high-risk frontline duties.

After losing in the semifinals of the Queen's Blade tournament, Claudette unexpectedly ascends to the throne when the victor, Leina, relinquishes the title. Her reign initially introduces progressive reforms: she spearheads technological progress through "Wizard Stones," invalidates the traditional aristocracy to foster social mobility, and governs with perceived justice. However, her rule rapidly descends into tyranny. She abolishes the Queen's Blade tournament, aligns with the malevolent Marshland Witch, and enforces laws with extreme ruthlessness. Opposition faces brutal military suppression, and punishments are delivered without leniency, reflecting her rigid nature. Her physical transformation includes a more imposing white headpiece, a white bodysuit with an open breastplate, and a flowing cape, symbolizing her elevated yet corrupted authority.

Claudette's relationships with her sisters are complex. While outwardly protective, she resents Leina for abandoning her duties as family heir, intensifying their rivalry. She holds genuine affection for Elina but remains incapable of articulating it. The Vance family dynamics are deeply dysfunctional, shrouded in secrecy—none of the sisters discover their mother's killer was Queen Aldra, a truth known only to their father and the mercenary Echidna. Their shared history as "Lonely Rich Kids" without external friendships compounds their emotional isolation.

In the *Rebellion* storyline, Claudette's tyranny sparks a resistance led by Annelotte. The conflict culminates in her defeat. Revelations about the Swamp Witch manipulating her mother, Werbellia, imply potential mitigating factors behind her actions. Her arc concludes with a degree of redemption, acknowledging external influences contributing to her descent. Claudette embodies themes of duty, repressed emotion, and the corrosive impact of power, transitioning from respected military leader to feared monarch before facing downfall.