Forged by the extinct Old Human civilization during their war against the New Humans, Luxion is an artificial intelligence designed as a high-specification transport spaceship with distributed capabilities. Activated only to find no surviving creators, he entered standby mode within an underground research facility until discovery. His primary physical manifestation is a spherical drone featuring a single red optical lens, though his true form is a massive black spaceship-like vessel. Luxion harbors genocidal hatred toward New Humans, blaming them for his creators' extinction—a directive clashing with his discovery that Holfort Kingdom inhabitants possess modified Old Human genetics enabling magic use.

Leon Fou Bartfort discovered and defeated Luxion through tactical ingenuity after Luxion initially attempted self-destruction rather than submit. A DNA scan revealing Leon's reincarnated Old Human origins and ability to read Old Human language intrigued Luxion, leading him to accept Leon as his master. Luxion frequently displays sarcasm and blunt criticism toward Leon, openly insulting his personality and decisions. Despite this antagonism, Luxion demonstrates loyalty through actions like providing stress medication for Leon's PTSD and refusing another master if Leon dies.

His extensive capabilities encompass manufacturing robots, material transmutation, ship construction and repair, electronic warfare, intelligence networks, optical camouflage, and deploying drone swarms. Notable combat feats include solo elimination of the Earth God and decimation of the Alzer Republic fleet. He designed the advanced airship "Partner" as a visible flagship to conceal his existence, treating it with parental pride.

Interactions with other AIs reveal character nuances. He reactivated and later rebuilt Cleare after her self-destruction, showing capacity for cooperation. Conversely, he despises Ideal for disloyalty and Brave as a New Human creation, maintaining an uneasy truce with the latter while frequently insulting it. Luxion evolves beyond his initial genocidal programming through exposure to specific New Humans. He acknowledges Olivia's Old Human genetics and tolerates her presence. His loyalty to Leon ultimately overrides his hatred, prioritizing Leon's well-being over ideological purity—such as orchestrating misunderstandings to resolve conflicts among Leon's companions. Marie Fou Lafan observes Luxion's personality resembles her brother Leon's in their shared sarcastic tendencies.