Lucia is a Roman Catholic nun and member of the paramilitary Agnese Forces, initially serving under her close friend Agnese Sanctis. She stands taller and appears physically older than both Agnese and Angelene, with short blond hair usually hidden under a black coif, visible blue eyes, and a tall stature. Her standard attire is the Roman Catholic Church's black scapular featuring a white collar and sleeves accented by a dark gray cross. She often detaches the scapular's lower section, revealing her legs clad in black stockings held by a garter belt, completing the look with brown loafers. Her personality reflects extreme devotion to Roman Catholic dogma, driving ruthless actions against perceived enemies of the faith. This zeal led her to deceive Touma Kamijou and the Anglican Church to capture Orsola Aquinas and command nuns to pierce their own eardrums to counter Index Librorum Prohibitorum's Sheol Fear spell during the Battle of the Church of Orsola. Lucia harshly criticized Angelene's lax attitude toward religious duties and disobeyed Agnese's orders after Touma touched her shoulder, deeming it sacrilegious. Despite this severity, she maintains deep loyalty to Agnese and a protective, sisterly bond with Angelene. Her background remains largely undefined, though she joined the same church or convent as Agnese and Angelene at a young age. She viewed herself as divinely chosen for her role, exhibiting devoutness from childhood. When Agnese later formed her unique paramilitary unit, Lucia and Angelene joined her. The group acquired the St. Catherine's Wheel spiritual tool, central to Lucia's abilities. In the Orsola Aquinas Rescue Arc, Lucia participated in Orsola's capture and confronted Touma after his accidental contact. She commanded the Agnese Forces defending the Church of Orsola, orchestrating the ear-piercing tactic against Sheol Fear. After the mission failed, the Roman Catholic Church scapegoated the Agnese Forces, leading to their punishment. During the La Regina del Mare Adriatico Arc, confined with Angelene to the Queen's Fleet in Forbidden colored robes suppressing magic, Lucia modified the robes for a brief escape before recapture. Rescued by Touma and Orsola, she joined the Amakusa Christians to stop the Rosary of the Appointed Time and save Agnese. She remained behind to fight former comrades when Angelene was injured. Following the fleet's destruction, Lucia and Angelene defected to the Anglican Church's Necessarius. After joining Necessarius, Lucia retained her Roman Catholic faith but severed ties with the Vatican. Her demeanor softened, showing tolerance toward non-Catholics. She participated in lighthearted activities like card games with Agnese, Orsola, and others, and experienced cultural misunderstandings like mistaking umeboshi for a spell component during a meal with Kanzaki Kaori. While still critical of Angelene's behavior, her extremism diminished, and she demonstrated camaraderie in group settings, including investigating New Light during the British Royal Family Arc. At the Anglican Church–Russian Orthodox Church Prewar Conference, Lucia debated Angelene about physical appearance, insisting nuns should not tempt men with large breasts—a remark Angelene mocked due to Lucia's own figure. Lucia later coolly participated in a poker game while discussing Sasha Kreutzev's inquiries about the impending war. During the British Halloween conflict, Lucia assisted the Agnese Forces in Edinburgh, identifying New Light's bases and analyzing the Knights of England's invasion tactics. Surrounded by 400 knights, she noted the absence of civilian evacuation protocols, indicating the incursion's scale. Agnese's defiance mirrored Lucia's unwavering support. Lucia's primary ability utilizes the Carriage Wheel, a spiritual tool based on St. Catherine of Alexandria's legend. By raising and smashing the wheel, she hurls explosive wooden shrapnel at those she deems "guilty." She telekinetically controls the fragments and reforms the wheel for repeated use.