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.
He makes also a cameo appearance into Season Five of Once Upon A Time, living into the Land of Untold Stories.