Athos serves as a rational and level-headed member of the King's Musketeers alongside Porthos and Aramis, acting as the group's most experienced figure. His formidable swordsmanship enhances their effectiveness in battle. Following an initial duel and reconciliation, Athos develops a protective mentorship toward d'Artagnan, evolving into a strong camaraderie where he treats the younger man like a brother.

This adaptation omits Athos's original literary backstory as the Count de la Fère, his marriage to Milady de Winter, his noble origins, destitution, and marital betrayal. Functioning primarily within his role as a musketeer, his past remains unexplored, with no references to aristocratic lineage or tragic romance.

Athos participates in critical missions, including retrieving the Queen's diamonds from England. He engages in enemy mine collaborations, aiding the imprisoned Cardinal Richelieu and Rochefort during the Man in the Iron Mask crisis to prevent King Louis XIII's execution. He also attempts a prison break with Rochefort by loosening cell stones, though their transfer halts the plan.

In the original anime arc, Athos confronts the revolutionary Iron Mask and witnesses pivotal events: the King's replacement by his twin brother Philippe, Milady's reversion to villainy despite prior redemption, and ensuing political turmoil. He ultimately joins forces with former adversaries like Rochefort and the Cardinal's guards to defeat Iron Mask and restore order.

The feature film "Aramis no Bōken" focuses on Aramis's backstory and a murder conspiracy investigation involving Catherine de Médicis. Athos appears alongside the other musketeers but receives no significant development or expanded background, remaining peripheral to the central plot. No spin-offs or additional media expand his character beyond the television series and this film.