Nathalie Sancoeur/History

Season 1
In "Ladybug & Cat Noir (Origins - Part 1)", as Adrien attempts to enter Collège Françoise Dupont, Nathalie along with Adrien's bodyguard stop him, reminding him that his father doesn't want him going to school, though Adrien insists that's what he wants. When Adrien spots Master Fu tripped and unable to reach his cane, he runs to help him, therefore allowing Nathalie and the bodyguard to block the steps leading into the building and take him back home. Later, Nathalie, while homeschooling Adrien, quizzes him on history until Gabriel interrupts and firmly tells Adrien that he will not be going to school before exiting. Nathalie offers to end the homeschooling for the day, though Adrien sadly runs up to his room before she can finish.

In "Stoneheart (Origins - Part 2)", Nathalie notices that Adrien is not in his room and informs Gabriel, who scolds her and the bodyguard for failing to notice Adrien leave. Just as Adrien is about to enter the school, Nathalie begs him not to as his father will be furious, though Adrien tells her to tell him that she came too late and enters. Nathalie tells the bodyguard she'll handle it. The next day, per request by Nathalie, Gabriel allows Adrien to continue going to school, to which Adrien thanks both her and his father.

In "The Bubbler", after giving Adrien his schedule, Adrien asks her if his father approved his request for a birthday party, to which Nathalie informs him that he didn't and wishes a saddened Adrien a happy birthday. Later, Nathalie answers the doorbell when Marinette comes over to the Agreste mansion to deliver her birthday gift to Adrien, telling her to put it in the mailbox. Gabriel asks her through an intercom who was there, to which Nathalie tells him that it was a friend of Adrien's delivering him a birthday gift. Gabriel therefore asks Nathalie if she got Adrien a gift on his behalf. Nathalie nervously claims that Gabriel never asked her to do that, though Gabriel yells at her that he did. Nathalie agrees to get it done, and after Gabriel hangs up, she decides to pass off Marinette's gift as Gabriel's. Then Nino comes by and Nathalie witnesses him requesting that Gabriel allow Adrien to have a birthday party and Gabriel's cold refusal. After Nino is akumatized into Bubbler, Nathalie is one of the many adults seen floating in bubbles in the sky. After Bubbler's defeat, Gabriel asks Nathalie if Adrien liked his gift, to which Nathalie says that she'll check. She then approaches Adrien and hands him Marinette's gift, claiming that it's a birthday present from his father.

In "Mr. Pigeon", during Gabriel Agreste's derby hat competition, Nathalie introduces herself to Mr. Damocles and presents Gabriel, who is judging the competition via video chat on her tablet. She takes Gabriel around as he observes all the hats and eventually declares Marinette the winner.

In "The Mime", Nathalie is sitting next to Adrien in the backseat of the Agreste car as they head to the premiere of The Mime's Extraordinary Adventures. She receives a phone call from Gabriel informing her that he will not be able to make it to the show. After hanging up, Adrien asks her if his father is flaking, to which Nathalie says yes but also informs him that his father reserved front row seats. Then Ladybug shows up as she battles Mime and tells everyone in the car to get out and find a safe hiding spot. Nathalie is then seen running away along with the bodyguard.

Season 2
In "Santa Claws",

In "The Collector",

In "Glaciator",

In "Style Queen (Queen's Battle - Part 1)", at Gabriel Agreste's fashion show, she catches Marinette as she attempts to sneak out and leads her to the dressing rooms. On the way, Marinette bumps into Audrey Bourgeois, who notices Marinette's hat and asks what it is, though Nathalie informs her that they must keep going before Marinette can deny that the hat is hers. Once they arrive inside Adrien's dressing room and Marinette gives Adrien the hat, Nathalie leads Marinette to the front row seats. She spots Audrey and tells her that she has a second row seat, which infuriates Audrey as she only accepts front row seats. She attempts to fire Nathalie, but Nathalie reminds her that she works for Gabriel, not her. Audrey attempts to call Gabriel but he doesn't answer, prompting Nathalie to comment that she assumes she isn't fired, causing Audrey to furiously storm out and be vulnerable for akumatization into Style Queen by Hawk Moth. After Style Queen’s defeat, Nathalie contacts Gabriel and comments on the big risk he took involving his son getting turned into a glitter statue.

In "Queen Wasp (Queen's Battle - Part 2)", when Gabriel decides to quit being Hawk Moth and sadly sulks over his wife, Nathalie notices and hugs him. Later on, when Gabriel changes his mind about quitting being Hawk Moth, Nathalie confronts him about it. Gabriel tells her that he can’t give up, as he misses his wife too much. Though Nathalie understands, she can’t help but feel sad for him.

In "Catalyst (Heroes' Day - Part 1)",

In "Mayura (Heroes' Day - Part 2)",