Role in ReconnectMim was once one of Yen Sid's apprentices in magic, but, being higly insane and greedy for power, she ended up joining Melena's secret alliance under the Horned King's guidance and tried to kill the old keyblade master, but she, alongside the rest of her allies, were defeated and banished back to their worlds as punishment. In her anger, Mim became one of the Horned King's apprentices and learned the art of dark magic. Upon returning to her world after completing her training, she re-encountered Merlin and entered a long war with him that eventually destroyed their world of Camelot after many years of fighting. Mim managed to survive her world's destruction and rejoined her old ally Melena, now called Maleficent, in trying to capture the Heart of All Worlds: Kingdom Hearts. Like Pete, Mim was assigned to gather an army for Maleficent to use in conquering the worlds, but she found out about the evil faerie's death immediately afterwards by Hades, forcing Mim into hiding within Traverse Town, and then back into her home world once it was restored by Sora closing the DTD. For two years, Mim spent her time in solitude by playing card games with herself. When Maleficent returned after her defeat in KH 3D, she re-recruited Mim to her alliance in the hopes that an army of Disney Villains would finally be enough to conquer Kingdom Hearts at last.
During Sora's third visit to Camelot, Arthur is transformed into a bird by Merlin, only to end up in the home of Mim. Madam Mim initially tries to convince Arthur that she is better than Merlin, hoping to corrupt the future king of Briton on Maleficent's orders, but Arthur remains unconvinced, citing that Merlin uses his magic for good. This result in Mim deciding to try and destroy him, being that she sees all good things as bad ("Yes, and in my book, that's bad!"). She transforms into a cat and captures Arthur, but cannot destroy him as Merlin and Sora, warned by Archimedes, appear and interrupt her. This results in a "Wizards' Duel" between her and Merlin for the young boy's life in which both parties transform into a series of animals. Mim cheats throughout the entire duel, breaking each of her self-set rules in turn. Mim initially has the upper hand, especially after transforming into a dragon. This leads to a battle between Mim in her dragon form and Sora, that ends up with both of them weakened. However, Merlin helps out Sora by transforming into a germ and infecting Mim. She is last seen in her home, recovering from the disease. Merlin advises her to get plenty of rest and sunshine, opening a hole in her roof as he speaks. As Merlin, Archimedes, and leaves, Mim rants about how much she hates sunshine.
Later on, Mim, cured of her chicken pox, is recruited by Pete into his private army of villains against Xehanort's 13 darknesses, being given her own keyblade and keybearer outfit as a gift from Maleficent.
Madam Mim is a very powerful witch who is equal or more powerful than Merlin himself; however overconfidence is her biggest flaw. She is an old rival of Merlin, and holds him in disregard. Mim is presented as boisterous, mischievous, and rather conceited, a sorceress much impressed with her own power who delights in causing trouble. She is also a somewhat morbid character with distaste for sunshine and all things wholesome.
Powers and Abilities
Madam Mim claims to be more powerful than Merlin. She is shown doing a few minor tricks, like withering flowers. The main ability she displayed however was her shape-shifting skill with which she can take the form of anything she wants. During her introduction scene, she changes into a cat, and magically makes herself uglier, and then beautiful. During her wizard duel with Merlin, she turned into: an alligator, a fox, a hen, a elephant, a tiger, a rattlesnake, and a rhinoceros, all of which were colored pink and an ugly, purple, fire-breathing dragon.