Lucius Orgueille is the oldest son and heir of the Orgueille house, a low-ranked noble family from the Beltram Kingdom. Before his house fell from favor, he served as a candidate for the King's Sword, the kingdom's elite guardian position, alongside Alfred Emerle. After the downfall of his family, Lucius worked as an adventurer. At some point, he encountered and murdered Ayame Karasuki, the mother of Rio, which set the central revenge plot of the story in motion. Following this act, he left the Beltram Kingdom and founded the mercenary group known as the Heavenly Lion, also called the Griffins. This small band of elite warriors became legendary across the Stralh region for its victories, and many adventurers sought membership. Years later, the group's official activities ceased, with its members, including Lucius, being lent to the antagonist Reiss Vulfe for covert assignments. Rumors circulated that the group had disbanded, but its fame endured even among those not involved in warfare.

Personality-wise, Lucius is proud, cruel, and deeply sadistic. He loves to display his strength and takes pleasure in humiliating those weaker than himself. As a young man, he had little regard for noble responsibilities or loyalty, preferring to associate with disreputable company and resenting any form of constraint. Alfred remembered him as someone who disliked being tied down and lacked consciousness as a noble, but whose talent with the sword was undeniable. These traits carried into his adult life as a mercenary leader, where he continued to act on impulse and self-gratification.

Lucius's primary motivation appears to be personal freedom and the pursuit of strength for its own sake, without concern for morality or the consequences of his actions. He is driven by a desire to prove his superiority and to live without the restrictions that noble society once imposed on him. He shows no remorse for the harm he causes, viewing others as tools or obstacles.

Within the story, Lucius serves as a major antagonist and the primary target of Rio's quest for vengeance. His murder of Ayame and his subsequent actions directly motivate Rio's journey. He also acts as a foil to Rio, representing the unrestrained use of power that Rio must overcome. Lucius's group, the Heavenly Lion, plays a background role as a legendary but now inactive mercenary force, occasionally providing muscle for larger schemes.

Key relationships include Alfred Emerle, who once competed with him for the King's Sword position and later regards him with caution. His connection to Rio is one of hunter and prey, as Rio pursues him relentlessly. Lucius also collaborates with Reiss Vulfe, lending his mercenaries for secret missions. His leadership of the Heavenly Lion defines his professional identity, and his subordinates look up to him despite his cruelty.

In terms of character development, Lucius remains largely static throughout the narrative. He does not undergo a moral change or redemption; instead, his role is to be confronted and defeated as part of Rio's character journey. He embodies the antagonist who will not be reasoned with, forcing a direct clash.

Notable abilities include exceptional swordsmanship, honed from his time as a King's Sword candidate. He is physically muscular and strong, likely employing body-strengthening magic common in the Stralh region. He also wields an enchanted sword, which enhances his combat capabilities. His leadership and tactical skills enabled him to build and maintain the feared Heavenly Lion mercenary group. Overall, Lucius Orgueille is a formidable warrior whose ruthless nature and pivotal actions against Rio make him a central figure in the series' conflict.