Lucrezia Noin served as an OZ lieutenant during the Earth-space colony wars, advancing its military agenda until Treize Khushrenada’s death and OZ’s collapse shifted her path. She co-founded the postwar Preventers, an interstellar security force where her operational callsign "Fire" symbolized her proactive countermeasures against destabilizing threats. A skilled pilot, she commanded first a green Aries mobile suit before transitioning to a white Taurus commander unit under the Sanc Kingdom’s banner.

During the Barton Foundation’s rebellion, she allied with former rivals, including Gundam pilots, to dismantle resurgent militant groups. Her strategic partnership with Zechs Merquise proved pivotal during high-stakes missions, such as dismantling the Mariemaia Army’s headquarters. Expanded media, like *Mobile Suit Gundam Wing: Endless Duel*, depicted her piloting the Mercurius mobile suit—a deviation from her primary series role. Postwar interquel narratives such as *Blind Target* outlined her Preventers activities without granular specifics, though her tactical approach consistently prioritized precision to minimize collateral damage.

Noin’s evolution from soldier to peacekeeper underscored her adaptability, anchored by alliances with figures like Zechs and Relena Darlian to stabilize volatile political transitions. Her combat career concluded with the Earth Sphere Unified Nation’s demilitarization mandate, which decommissioned all mobile suits, aligning with her commitment to lasting conflict resolution.