Mesmero - Rank 7 in the House of X's leadership, an Omega Level telepathic Mutant with a specialty towards enslaving and controlling others. Born to unknown parents in the depths of Latveria's deepest slums, she was abandoned shortly after her birth since her mutation manifested extremely early, revealing her horrifying appearance to her parents long before would be expected for a Mutant, leading them to believe she was a devil child. She was left abandoned in the woods, and only survived by subconsciously using her telepathy to control the local wildlife in the forest to bring her to shelter and give her food daily, as well as grooming her and the like. As such, she grew up completely estranged from the rest of the world, and only managed to rediscover civilization when she was around 8 years old, confused as to what this new world she discovered was, and why it was so familiar to her. Having already long honed her telepathic abilities in the woods, she quickly mind controlled a number of people and forced them to attend to her, particularly in the field of teaching her language, which she eventually completely came to understand. As she grew, she continued to be disconnected from the world around her despite learning the language, her history living in the wilds preventing her from empathizing with the citizens of Latveria, and instead usually mind controlled them to serve her purposes - bringing her money, killing her enemies, etc. In particular, she was prone to forcing girls to be in love with her whenever they struck her fancy, only to command them to kill themselves whenever she inevitably found some imperfection to them that, no matter how minor, soured her opinion of them. Because of the strength of her mutation, she was able to mind control hundreds of people in the city of Latveria, all without raising the suspicions of the military police or the Doombots that regularly prowled the streets.

Her appetite for control grew greater and greater until almost the entire city of Latveria was under her power, and seeking to make the nation into her own personal kingdom, attacked the central fortress of Latveria, expecting it to be easy after she had enslaved so many people and reprogrammed so many robots, only for the emperor of Latveria, Victor von Doom, to crush her rebellion with ease. When he faced the teenager responsible for the rebellion, he could smell she was an abandoned child and longed for little more than a place to call her own, and thus, instead of imprisoning her or killing her, he chose cruel mercy - banishing her into the outside world, where she would again be a stranger away from anything she considered home. Enraged and saddened by her failed plan, Mesmero's hunger and ambition only continued to grow, and she continued to enslave entire populations, to the point she eventually did have an ostensible kingdom in her own right carved from the many cities she had brought under her power, but still felt unsatisfied since it was neither her land of birth nor the world entire. It was when a woman who had telepathic power comparable to hers entered the city she called her throne did she join the House of X, astonished by Cassandra's power and seeing her as the closest thing to a kindred spirit she had ever encountered, as well as seeing her as an opportunity to finally claim the world she thought was owed to her - together. Mesmero's personality is extremely controlling and self centered, and aside from interactions with a few people like Cassandra or Proteus, thinks of things only in how they can serve/benefit her, putting her own desires and existence before everything else in the world. She cannot comprehend human sensibilities and is confused as to why everyone hates her, when all she does is strip them of this "free will" that seems to cause their world so many problems and ushers them into a life of certainty and peace.

She is obsessed with the concept of bonds, longing to have a genuine bond with anybody, which is why she constantly enthralls girls to serve as her lovers and rarely other bizarre matchups, such as brainwashing people to think they're members of her family or even her own children. If she sees a bond between two people that is very strong, she will be filled with incomprehensible envy.

She is extremely unstable, and it is the only reason why her rank isn't higher what with how strong her power is. She will command people to kill or mutilate themselves at the drop of a hat if they anger her sensibilities, and will fly into a complete, vindictive rage when anybody suggests this life she's created for herself is artificial. Despite this, she usually speaks with a stoic/emotionless tone of voice, even when extremely mad, and even when enraged her voice just becomes more harsh and vindictive rather than yelling or screaming. She truly cares for Cassandra and sees her as a mother figure, not caring in the least that Cassandra only views her as a tool. Befitting how she's the only other teenage member of the House of X's leadership, she's great friends with Proteus, often enjoying their sadistic games together. One could almost wonder if they have feelings for each other, but it is unlikely due to their tendency to use their powers to create brides for themselves instead of pursuing any romance together. She wears a mixture of a robe and a dress, layered between very light scarlet layers such as the undershirt and skirt, as well as a scarf, and somewhat thicker white layers such as an interwoven pseudo-coat with a giant red vertical eye marking on the back, as well as a secondary skirt on top of her main red skirt that is cut into four separate sections at her front and sides, each patterned with three horizontal red eye cut outs on them. She goes everywhere barefoot. Her hair is white and quite jagged and creepy looking, folding inward in a fashion that brings together dried up, curling leaves, spider legs, or a toothy maw, her mouth is wider than most people's (making her constant smiles rather disturbing), she has subtle fangs, and two columns three horizontal red eye markings are underneath her left and right eyes.

Her skin is ghost white, and her ESP is blood red. She has three eyes, two in the normal position and one vertical eye at the center of her forehead. Each of her eyes have strange red sclera that looks like several red, somewhat fleshy "rings"  or loops, all rotating in different directions and speeds, and the iris of each of her eyes is completely white, while the pupil is replaced with a second, vertical eye in each, stretching from the top to bottom of the iris, with black sclera and a yellow, swirling pupil. Her hairstyle normally hides her third eye, which is revealed when her telepathic power causes her hair to blow.