Athos was once a married nobleman. Athos learns his wife, Sabine bears the fleur-de-lis brand on her shoulder- a mark for execution. He betrays her to the authorities. Believing her to be dead, Athos is surprised to cross paths with his former wife, now a minion of Cardinal Richelieu. He and the Musketeers capture her and learn that her brother-in-law Count de Winter wishes to condemn her for the death of his brother- her latest husband. Visiting her jail cell, Athos tries to gain from Sabine information about the Cardinal's plans but fails. The next morning the Musketeers, D'Artagnan, and Count de Winter witness Sabine's execution by beheading. At the last minute, Athos saves Sabine from the Executioner's sword, begging her forgiveness for betraying their love. Moved by this, Sabine tells everyone all she knows about the Cardinal's plans and commits suicide by jumping off a cliff.
Athos was a man of calm and collected stature who took drinking very seriously (just as much as Aramis found death seriously.) He cares for his fellow Musketeers, as he also believes that while their duty is to protect the King and Queen, its his and the musketeers duty to protect each other. Athos was also a mentor and father figure towards d'Artagnan. Athos also genuinely loved Sabine, especially begging her forgiveness
Role in the film
When D'Artagnan appears and asks if this is the Musketeers' headquarters, Athos mentions that this was the Musketeers' as they had been disbanded. He is offended by D'Artagnan's behavior and challenges him to a duel, scheduled at noon. He takes Porthos and Aramis with him, who have also been challenged to a duel by d'Artagnan. They are interrupted by the cardinal's men, who intends to arrest the Three Musketeers and allow d'Artagnan to walk away. As they tell D'Artagnan to stay out of the fight, he reveals his name. Athos recognizes the name as the name of a fellow Musketeer, also called d'Artagnan. The Musketeers and d'Artagnan team up to defeat all forty men. Though Athos and his friends are impressed with D'Artagnan's fighting, they leave him behind while telling the young man to flee. However, hearing he will be executed, Athos, Aramis and Porthos rescue d'Artagnan from execution.
Making their escape, Athos, d'Artagnan, Aramis and Porthos steal the Cardinal's carriage and run off, with D'Artagnan and Athos in the driver's seat, where the latter is driving the horse's reins. As they make their escape, Porthos shares the wine that he found with Aramis with Athos but does not give one to d'Artagnan, as he is too young to drink it. During the escape, Athos recognizes that D'Artagnan has learned that King Louis is in danger, as the Cardinal Richelieu had released his agent, Milady de Winter, sending her to England to negotiate terms with the Duke of Buckingham. With this knowledge and that the Cardinal knows that D'Artagnan has this information, Athos realizes that now that he, Porthos and Aramis know, there is a price on all of their heads. The four men manage to escape the Cardinal's guard by sending the carriage in flames while taking the horses.
Later, the quartet stop the inn for the night, where Athos sits alone while drinking the ale obsessively. From far away, his fellow comrades are talking with other women, where Aramis and Porthos attempt to teach D'Artagnan about seducing other women. However, it fails miserably. D'Artagnan approaches Athos, and prepares a toast, proposing they toast to love. Athos then begins to tell d'Artagnan of his backstory of how he fell in love with a woman but she ended up betraying him. However, he does not acknowledge that it was him but a friend he once knew. The next morning, the quartet are chased by bounty hunters, who are out for the price on the Musketeers' and D'Artagnan's heads. The group separates, with Athos and D'Artagnan going one way and Aramis and Porthos going with the others. As they ride, Athos notes that d'Artagnan is a brave man like his father. This information shocks the young man, asking Athos if he knew his late father. Athos acknowledges he knew the young man's father based on reputation and that his death was mourned by other Musketeers (other than the one who betrayed d'Artagnan the Elder).
During their travel, D'Artagnan and Athos are ambushed on the road and they go into hiding while firing at the enemy. Athos realizes that one of them must escape. He coerces D'Artagnan (after threatening to shoot him) into riding off to stop the assassin from reaching a nearby village while standing his ground. D'Artagnan leaves his pistol behind while riding off. Athos is able to escape from his doomed fate and meets up with Aramis and Porthos. The trio goes to Calais. While Porthos and Aramis stop Milady de Winter's thugs and rescuing d'Artagnan (whom Milady had previously kidnapped). Athos stops Milady from leaving and calls her "Sabine," and is shocked to see her alive, where she reveals that the Cardinal rescued her from execution. She attempts to escape but she is cornered by Lord Armand de Winter, who charges her with murder for the murder of his brother, the late Lord de Winter. Later that evening, Athos visits the captive Sabine and asks her about the Cardinal's plan for the King. However, she refuses to answer when Athos cannot save her from execution.
The next morning, Athos saves her from beheading and asks for her forgiveness. Moved by Athos' apology, Milady reveals that the Cardinal plans to kill the King at his birthday celebration. As she commits suicide, Athos cannot help but feel sorrow for the woman he loved. He informs his fellow comrades that the king's life is in danger and they make their way to Paris.
Upon their arrival, Athos orders for d'Artagnan to find the assassin while he, Aramis and Porthos rescue the King and Queen from Armand Richelieu, who attempts to kidnap the king and Queen. However, Athos, Aramis and Porthos ambush the Cardinal, who is punched in the face by the King. In the aftermath of the film, after Louis says he owes d'Artagnan, Athos reveals that d'Artagnan asks for one thing: permission for him to join the Musketeers. Louis does as Athos recommends, thus making d'Artagnan an official member of the Musketeers.
After the celebration, Athos runs to fight of Girard and his brothers in order to protect d'Artagnan from the angered brothers.
Athos makes a cameo appearance into Season Five of Once Upon a Time, living into the Land of Untold Stories.
- Athos takes drinking seriously while Aramis takes death seriously.