Joseph de Gallia reigned as King of Gallia and wielded rare void magic, making him one of Halkeginia's few void mages. His familiar, Sheffield, acted as his agent in hunting other void mages.

Joseph was the elder brother of Charles de Orléans. After the previous king's death, the Gallian court split over succession, favoring the younger Charles for his superior magical talent, charisma, and leadership. Joseph orchestrated Charles's assassination to seize the throne. He then poisoned his niece, Charlotte de Gallia (Tabitha), intending to drive her insane. This plan failed when Charlotte's mother, the Duchess of Orléans, intervened and absorbed the poison, becoming permanently insane herself. The ensuing scandal forced Joseph to send Charlotte abroad under the pretense of education.

As king, Joseph pursued ambitions fueled by his void magic. He sought to capture Louise de la Vallière to exploit her void abilities, deploying Sheffield to track her. His broader goal involved triggering a cataclysmic event using void magic to shatter the world's existing order. In *Rondo of Princesses*, he targeted his niece Tabitha to eliminate her as a rival claimant to the Gallian throne. This culminated in a confrontation at Castle Alhambra where he again attempted to destroy her mind with a soul-destroying poison.

Joseph employed the void spell "Acceleration," though specific applications remain undocumented. His manipulation extended to geopolitical intrigue, including involvement in the war against Albion and schemes targeting Romalia. His reign fostered Gallian instability through familial betrayal and political repression.

Joseph met his end during the chronicled events. His death left a legacy of familial trauma and a destabilizing power vacuum in Gallia.