Nicolas de la Motte is a supporting antagonist in the story, primarily known as the husband of Jeanne de Valois-Saint-Remy and a member of the Royal Guard under the command of Oscar François de Jarjayes. He is based on the real-life historical figure Marc Antoine Nicolas de La Motte, a French adventurer involved in the Affair of the Diamond Necklace. In the narrative, he is depicted as a tall, muscular man with brown hair who typically wears his military uniform. His background is tied to minor nobility; he served as a gendarme before becoming part of the royal guard. He marries Jeanne in 1780 and becomes deeply entangled in her schemes.

Personality-wise, Nicolas is portrayed as ruthless yet naive, weak-willed, and cowardly. He is madly in love with Jeanne, and this devotion is his primary driving force. He is willing to commit crimes, including theft, desertion, and attempted murder, all in an effort to please her and advance her ambitions. His lack of moral strength and his tendency to follow Jeanne without question often cast him as a weak and contemptible figure. He is not particularly intelligent or cunning on his own, but his physical strength and loyalty make him useful to Jeanne’s plans.

His role in the story centers on the diamond necklace affair, where he actively participates in the fraudulent scheme that brings scandal to the French court. He travels to London to sell the diamonds, and later, when the plot is exposed, he is condemned to the galleys in absentia after fleeing to England. After the French Revolution, he returns to France and resorts to blackmailing the family of Cardinal de Rohan, threatening to publish damaging memoirs unless they pay him. In the narrative, he also attempts to kill Oscar, further solidifying his role as an antagonist.

Nicolas’s key relationship is with his wife Jeanne. He is completely submissive to her, and she exploits his love and devotion for her own ends. He serves under Oscar as a soldier but has no close bond with her; instead, his loyalty to Jeanne puts him in direct opposition to Oscar. He does not experience significant character growth; throughout the story, he remains a morally compromised individual driven by his infatuation and self-preservation. He survives the revolution by staying abroad and later continues his life through extortion, never achieving a redemptive or noble end. His notable abilities are limited to physical prowess and a stubborn, if misguided, loyalty, but his lack of courage and independent judgment define him as a tragic and unsavory figure.