Lucius Oriflamme, known as Luca, is a young vampire aristocrat destined to inherit the Grand Dukedom as heir apparent. Despite his youth, he wields considerable political influence, though his uncle August Ruthven handles his official duties. Luca possesses the appearance of a prepubescent boy, with short reddish-brown hair featuring distinct cowlicks, large upturned green eyes, and a round, childlike face. His attire consistently reflects his noble status, such as a green mantle detailed in silver worn over a white shirt and black shorts. Outwardly calm, responsible, and mature, Luca harbors a contrasting nature prone to intense outbursts when those he cherishes are threatened. He is fiercely protective of his chevalier, Jeanne, reacting aggressively to perceived harm against her. This protective instinct triggers explosive pyrokinesis, causing flames to erupt from his body during emotional distress, an ability he struggles to control. He often masks his childish tendencies but betrays nervousness by clutching his clothes or belongings. His core motivations are family and loyalty. He confronts Vanitas and Noé Archiviste in Paris to seize the Book of Vanitas, believing it could cure his older brother Loki, a curse-bearer imprisoned due to his corrupted true name. When Vanitas refuses and insults him, Luca orders Jeanne to attack, later expressing regret and apologizing to Noé for his impulsiveness. At the Bal Masqué, he witnesses Charlatan's attack, powerless as Naenia torments Noé. He later asserts his authority in the senate to shield Jeanne from execution after the Gévaudan incident, declaring her his bourreau under his protection. Luca's relationship with Jeanne is central. Fiercely devoted, he often accompanies her on missions and reacts vehemently to Vanitas's romantic advances. Learning of Jeanne's feelings for Vanitas during the Amusement Park arc causes him to panic; he drags her to Dominique de Sade for counsel and expresses a wish to mature quickly. He views Ruthven with trust and dependence as a parental figure and shares a close bond with his imprisoned brother Loki, visiting him regularly and initially seeking the Book primarily for his sake. Later, Luca grows slightly taller, symbolizing gradual maturation. He takes initiative by tasking Jeanne with locating the missing Dominique. Unresolved concern for the vampire queen Faustina surfaces visibly when Vanitas questions her existence, causing Luca distress at her bedside.