Dominique de Sade, known as Domi, is the youngest scion of the aristocratic Crimson Moon vampire de Sade family. Born in 1869 to the Count de Sade, she is also the granddaughter of the enigmatic Teacher, Noé Archiviste's guardian. Dominique grew up believing Louis de Sade was her older brother, visiting him monthly at Teacher's castle in Averoigne. During one visit, Teacher introduced the recently orphaned Noé, whom he had purchased. Dominique, Louis, and Noé formed a deep bond, befriending village children Mina, Fred, Fanny, and Gilles, and establishing a secret forest base. A turning point occurred when Dominique overheard maids discussing Mina's impending execution as a curse-bearer. She alerted Louis and Noé. Despite Louis initially dismissing rescue, they hid Mina in their base. Mina succumbed to her curse, attacked Fred, and lunged at Dominique and Noé. Louis intervened, decapitating Mina, but then succumbed to bloodlust himself, attacking the other children. Noé tried to restrain him, but Teacher arrived and beheaded Louis. Dominique witnessed helplessly. Following Louis's death, Dominique gave Noé a chest Louis had instructed her to pass on "when the time comes." Noé collapsed upon seeing the wooden stakes inside, unconscious for two days. Dominique stayed by his bedside until her sister Veronica arrived. Veronica revealed that Dominique and Louis were twins, an evil omen; their father randomly chose Dominique to live, sending Louis to die, but Teacher intervened, taking Louis for "tests." When Noé awoke, he mistook Dominique for Louis, embraced her, called her by Louis's name, and collapsed again. This plunged Dominique into depression, convinced her family and Noé preferred Louis's survival. She blamed herself entirely for his death, developing an extreme inferiority complex. She adopted Louis's masculine speech patterns, cut her hair short, and dressed in male attire to emulate him. Dominique projects a confident, flirtatious, and authoritative exterior. Upon reuniting with Noé in Paris, she declared herself his fiancée and openly flirts with women like Nox and Jeanne. She acts protectively towards those she cares about, particularly Noé and later Jeanne, often disregarding their wishes. She deeply distrusts Vanitas, seeing him as a corrupting influence on Noé, and threatens, interrogates, and stalks him. Behind this facade, she is deeply insecure and prone to self-loathing. She fakes competence in social situations, like giving Jeanne dating advice despite lacking experience. Her elder siblings, Veronica and Antoine, belittle her, calling her a failure and mocking her affections, reinforcing her low self-esteem. Her guilt manifests as a persistent belief her existence is a mistake, culminating in a suicide attempt where she jumps from a Ferris wheel, stating she wishes she had died instead of Louis. Jeanne intervened to save her. Physically, Dominique is tall and slender with pale skin, a defined hourglass figure, broad shoulders, a small bust, and wide hips. She possesses the golden eyes of Crimson Moon vampires, which occasionally turn red. Her black wavy hair falls past her hips with long central bangs. After Louis's death, she adopted a masculine style: black button-up shirts, white tailcoats with gold accents, black thigh-high boots, a purple sash holding a rapier sheath, and purple gloves. As a child, she closely resembled Louis but favored dresses and wore her long hair often in a bun. As a vampire knight serving Carbunculus Castle, Dominique possesses standard vampire strengths—enhanced speed, endurance, and physical power via World Formula interference. Her combat skills are proficient, enabling her to subdue multiple vampires. Her primary weapon is a rapier, and she demonstrates precision knife-throwing. She inherited the de Sade family's cryokinetic abilities, manipulating ice by rewriting the World Formula. Unlike her destructive siblings, she uses this power with restraint, creating ice shards to trap or protect rather than kill. Her ice proved strong enough to withstand a falling Ferris wheel. Dominique's relationship with Noé is central. Her romantic feelings for him began in childhood; his reciprocation remains unclear. She prioritizes his safety, dragging him from Paris to Altus and blaming Vanitas for endangering him. She allows Noé to drink her blood, deepening their bond through the Archiviste clan's memory-reading ability. After Jeanne saves her, Dominique forms a close, affectionate friendship, buying her expensive gifts and offering support despite societal disapproval of Jeanne's bourreau status. Her family interactions are strained: Veronica and Antoine belittle her, her father remains distant, and her grandfather, Teacher, neglected her and enabled the trauma surrounding Louis's death.