Mayura

"They've been keeping you from achieving your dream for way too long. I will go to any length to end the reign of Ladybug and Cat Noir!"

- Nathalie to Hawk Moth. "Hawk Moth...I am Mayura. You're up against the world, plagued by your deepest, darkest despair. Let me help you! (Hawk Moth: No! Don't do that!) Let your despair be embodied in a powerful protection!"

- Mayura introducing herself to and using her powers on Hawk Moth. Nathalie Sancoeur, later known as Mayura and Catalyst in her akumatized form, is the secondary antagonist of Miraculous: Tales of Ladybug and Cat Noir. She is the assistant of Gabriel Agreste/Hawk Moth, who manages his mansion and takes care of his son Adrien Agreste/Cat Noir. However, she later decides to use the Peacock Miraculous to help Hawk Moth in his quest to steal Ladybug and Cat Noir's Miraculouses.

She was voiced by Nathalie Homs in the original French dubbed version, and by Sabrina Weisz in the English dubbed version.

Appearance
As Nathalie, she stands at an average adult height, and her eyes are a dull blue. Her hair is black and pulled back into a bun, and the hair on the right side of her head is dyed red. On her face Nathalie has glasses with black and red striped frames and on her eyes she has periwinkle eye shadow. She wears a red turtleneck sweater, a black dress jacket, black pants, and black high heel shoes. She also has round creamy white earrings.

As Mayura, her eyes have pink irises and sclerae that are pink which fade into dark indigo, and there is black liner around her eyes, resembling glasses. Her skin is a light indigo and her hair is dark blue, and part of it curls up underneath her left eye. She wears a peacock feather-like cocktail hat, being blue and tear-shaped with a light pink mark in the center and a light blue, translucent veil over her right eye. She wears a blue dress with a fuzzy black collar and sleeves that end in a point on the back of her hand. The dress appears to have a set hexagonal texture. The bottom of the dress has a front slit skirt, and the end of the skirt has rounded points with dark blue, light pink-centered spots, resembling a peacock's tail feathers. The rounded points are edged with translucent, light blue material. Underneath the dress, she has translucent indigo tights that are opaque from the knees down, making the opaque section resemble high heeled boots. She holds a blue hand fan, which is similar in design to the end of her skirt, and a peacock feather-like object in her other hand.

As Catalyst, she has has periwinkle skin. Over her head, while leaving her mouth exposed, she wears a black helmet with a red visor with black edges and a red spike pointing towards the back of her head. Catalyst also wears a black dress suit with stiff shoulders, including a dark red front and swan neck collar that features a red downward arrow-shaped section in the center. The sleeves cover her entire arms, with the tips of her fingers fading into red. Also, Catalyst has pocket-like ridges on each side of her hips, and her pant legs come down to her feet, having red high-heels, soles, and tips.

Nathalie Sancoeur
Nathalie possesses a rather cold and distant demeanor, very rarely showing her emotions around others. She is consistently serious, organized and diligent in performing her duties as Gabriel's assistant, yet is otherwise cordial and professional when it comes to dealing with others, such as reasoning with either Adrien or Gabriel when they act inconsiderate or emotionally (typically in relation to one another) or when assisting Ladybug with protecting Gabriel in "Simon Says". She can also be extremely fearful of disappointing Gabriel, panicking after realizing she forgot to get Gabriel a birthday gift for Adrien in "The Bubbler", and quickly deciding to disguise Marinette's scarf as a gift from the former instead. She seems to care greatly about Adrien in general, and does her best to provide for the Agreste family.

As shown in Season 2, Nathalie is not only dedicated to but incredibly loyal to Gabriel, as she is not only aware of his activities as Hawk Moth but openly supports him in his efforts to steal Ladybug and Cat Noir's Miraculouses. As such, she seems to be slightly sociopathic, having almost no concern for the consequences of Hawk Moth's actions, not even when they affect her directly. Like Gabriel, she also has a hatred of Ladybug and Cat Noir (though to not nearly to the same level) and wants to see them defeated, fully accepting Gabriel's plan to akumatize her and recreate most of his akumatized villains in "Catalyst (Heroes' Day - Part 1)", taking sadistic joy in fooling the heroes into thinking they can win all the while.She is furthermore willing to take any risks if it means protecting him, leading to her deciding to use the Peacock Miraculous to help him escape capture.

Mayura
As Nathalie's alter ego, Mayura still shows some loyalty and empathy towards Hawk Moth, by preventing Ladybug and her teams from stopping Hawk Moth. However, she seems to possess a more cold and calculating demeanor by not showing any form of emotion. (Unlike when she was Nathalie and Catalyst, because they both possess a limited temper.)

Pre-Series / Season 1
Though Mayura herself was absent during this time, her civilian identity, Nathalie, was usually seen at the Agreste mansion alongside her boss Gabriel Agreste and Adrien's bodyguard.

Season 2
In the episode "The Collector", it is revealed that Nathalie is aware that Gabriel Agreste is Hawk Moth when she asks the latter why he went after the book which Adrien had lost earlier if he already had another one, to which Gabriel answers that he had to hide his secret identity from Ladybug and Cat Noir.

In the episode "Catalyst (Heroes' Day - Part 1)", Nathalie helps Hawk Moth to get Ladybug and Cat Noir's Miraculouses by letting him akumatize her into Catalyst, a power-enhancing supervillain. Then Nathalie, as Catalyst, turns Hawk Moth into Scarlet Hawk Moth, boosting his powers so that he can create as many akumas as he wants.

Mayura makes her debut in the final episode with the same name "Mayura (Heroes' Day - Part 2)". After seeing that Ladybug and Cat Noir defeated Scarlet Hawk Moth and the scarlet akumatized villains, Catalyst becomes enraged. She takes the Peacock Miraculous and transforms herself into Mayura in order to help Hawk Moth. She then helps him escape the heroes. Later, a weak Nathalie is shown with the Peacock Miraculous alongside Gabriel Agreste.

Season 3
She will appear in Season 3 as the main antagonist, demoting Hawk Moth to be the secondary antagonist.

As Catalyst

 * Power Enhancement: Catalyst's main ability is to boost the powers of Hawk Moth, allowing him to Akumatize multiple people at once.

As Mayura

 * Guardian Creation: By infecting an object with one of her empowered feathers, Mayura can create a guardian from the emotions of the object's owner. It protects the person and can be dissolved by Mayura at the snap of her fingers.
 * Telepathy: Similar to how Hawk Moth can communicate with his akumatized victims, Mayura can also communicate with her victims telepathically.

Trivia

 * Mayura is the Sanskrit word for peacock, which is one of the sacred birds in Hindu mythology. It is also a contemporary Hindu name used in many parts of India.
 * While the villain is female, "mayura" is specifically the term for males, while "mayuri" is the term for females.
 * Unlike the other akumatized villains, Nathalie isn't akumatized due to negative emotions, but rather a real desire to help Hawk Moth.
 * Also, Catalyst is so far the only akumatized villian not to be defeated by the French Miraculous superhero team and the only one they are not aware of.
 * Strangely, she does not appear in "Chameleon", the first episode of Season 3, despite being the main antagonist of the third season. But the reason to her absence is mostly likely because of what happened with her in "Mayura".