Claude is Athanasia's father.

He is the current reigning emperor of the Obelian Empire. Claude usurped the throne by murdering Anastacius de Alger Obelia, his older half-brother, the son of the emperor and empress, and the proper heir to the throne.

As the youngest son of the royal family, Claude had an unhappy childhood and was treated as a spare, ignored, and neglected by Anastacius de Alger Obelia (his father, the current emperor at the time), his father's court, and all of his family. As evidenced by his name "Claude" meaning "crippled," he was born into a position of less power than his older brother. Royal names meaning "immortal" or "eternal" were typically reserved for kings and emperors (i.e. Anastacius, Athanasia, Aeternitas, etc). He is the son of an unnamed woman.

He was engaged to the daughter of a count, Penelope Judith, who was his first love. His fiancée kept delaying their engagement announcement as he wasn't first in line to the throne. Penelope eventually seduced Anastacius, the official crown prince and primary heir to the throne. After Claude caught the two of them in bed together, Anastacius started to mock and humiliate him even more than he used to. Claude went on to renounce his blood ties with the royal family. After becoming emperor, Anastacius killed Claude's mother and attempted to murder Claude. Out of anguish, he killed Anastacius instead and became the emperor of the Obelian Empire.

As emperor, Claude became distrustful and lived a debauched life, sleeping around with his concubines and killing whomever he wished. He met Diana, a dancer invited to the royal banquet, and deflowered her, and she eventually became pregnant with his baby. After Diana's death from childbirth, Claude massacred all of the concubines living inside of the Ruby Palace. Instead of Claude killing his daughter as well, he hesitated because her name was "amusing" and he wondered "how long this thing could live in accordance to its name."

Five years later, by an unforeseen concurrence, Claude happens upon Athanasia wandering around his palace after accidentally getting lost. Claude immediately recognizes her face, for it is almost identical to her late mother's.

Throughout the events of the story, Claude and Athanasia have tea together at 10 every morning. They become closer over time, and Claude starts to genuinely care for his daughter.