Lucia Fex serves as the brilliant engineer and mechanic behind Burning Rescue’s firefighting arsenal, designing and maintaining critical gear like the Mega Max firetruck and Galo Thymos’ Matoi Tech equipment. Driven by relentless curiosity, she thrives in high-stakes environments, treating active missions as live experiments. Her striking appearance combines pale skin, vivid blue eyes, and blonde hair accented with pink highlights, twisted into twin buns. She dons a lace-collared white lab coat, purple-and-black striped thigh-high stockings, and orange-lensed goggles, blending practicality with eccentric flair.

In *Galo-hen*, Lucia oversees Galo’s debut mission from the Mega Max, clashing with his impulsive tactics. When a trapped survivor, Thyma, triggers a fiery crisis by igniting Galo’s arm, Lucia’s quick deployment of ice missiles averts disaster. Post-mission analysis validates Galo’s risky approach, solidifying his standing within the team.

Throughout the main narrative, Lucia coordinates tactical responses to fires and Mad Burnish assaults, partnering with Galo to optimize his gear. After his imprisonment, she restores his damaged equipment and later douses his scorched body with cooling gel, propelling him back into combat. In the climax, she collaborates with Heris Ardebit to retrofit the Mega Max into a colossal drill, piercing Parnassus’ core to rescue Lio Fotia.

Her professional dynamic with Varys Truss centers on shared engineering ventures, while her rapport with Galo balances irritation and admiration, often testing prototypes on him. The enigmatic creature Vinny remains her constant companion, perched on her shoulder or workspace. Personal quirks include a locker brimming with lollipops, a candy machine, and gaming-inspired interfaces at her station. Labels hint at her enterprise, "Fex Industries," while concept art alludes to an earlier design with longer, Studio Trigger-esque hair, contrasting her finalized look.