Louis de Sade, born into the aristocratic vampire de Sade family, was the twin brother of Dominique de Sade. Vampire society deemed twins an omen of misfortune, prompting their father to arbitrarily recognize Dominique while condemning Louis to disposal. Their grandfather intervened, declaring the decision wasteful, and took Louis to raise in Averoigne under the pretense of an unspecified sickness. The rest of the de Sade family treated Louis as deceased for life. Raised in isolation at his grandfather's estate, Louis met Noé Archiviste when their grandfather purchased Noé at auction. Louis, Dominique, and Noé formed a close childhood bond, though Louis displayed a blunt, skeptical, and occasionally cruel demeanor. He distanced himself emotionally, rarely apologized, and masked inner turmoil with coldness. Louis and Dominique grew up believing Louis was one year older, unaware they were twins. His grandfather deliberately exposed him to texts about curse-bearers—vampires corrupted by malnomen (tainted true names)—fostering Louis's belief that his purported sickness destined him to become one. This triggered a psychological decline; Louis obsessively carved wooden stakes for Noé to use against him when the time came. His anguish intensified as he withdrew from Dominique and Noé, fearing his inevitable transformation. Tragedy struck when their young friend Mina was identified as a curse-bearer and sentenced to execution. Despite Louis's warnings that saving her was impossible, Noé and Dominique intervened. Mina transformed, killing one friend and endangering the others. To protect Noé and Dominique, Louis surrendered his true name to Naenia (a manifestation of malnomen), becoming a curse-bearer. He killed Mina and two other friends before losing control. In his final moments, he begged Noé to kill him with the carved stakes, insisting he preferred Noé as his executioner. When Noé refused, Louis attacked him, drinking his blood uncontrollably. Their grandfather intervened, decapitating Louis. Louis's death became a defining trauma. Dominique internalized guilt and self-loathing, believing she should have died. Noé harbored lasting resentment toward Naenia for exploiting Louis's desperation. Physically, Louis appeared androgynous with pale skin, center-parted black straight hair, and upturned golden-yellow eyes. He typically wore formal attire: white shirts, dark vests, bow ties, and black shorts. In relationships, Louis displayed protectiveness toward Dominique, though her acceptance within the family contrasted painfully with his disownment. With Noé, he alternated between pranks and genuine care, finding solace in their friendship despite initially dismissing Noé as naive. His dynamic with his grandfather involved wariness and avoidance, culminating in the grandfather's role as his executioner. Louis possessed standard vampire traits like enhanced strength and speed. Though unconfirmed, he potentially shared the de Sade family's cryokinesis (ice manipulation). His legacy persists through character motivations: Dominique's struggles with self-worth and Noé's quest to understand the Book of Vanitas are tied to his death. A fan theory speculates Louis survived decapitation and resurfaced as test subject "No. 70" in Dr. Moreau's experiments, citing parallels in Vanitas's backstory and a fairy tale Louis read foreshadowing his disappearance. This remains unconfirmed in official media.