Mitzi/Series

Season 1
Mitzi appears in the first episode. She is a school rival, and a neighbor to Bloom in Gardenia. Bloom is very annoyed by her self-imposed sense of overall superiority. She is first seen snubbing Bloom's consistent vacationing spot and while the workers were unloading her scooter she tells them to be careful and showed it off to Bloom, Bloom then says goodbye and rides her bike to the park having enough of her attitude. She then appeared again towards the end of the episode when Bloom and Stella were fighting Knut and his trolls and ghouls, watching TV and complaining about the noise.

In "A Great Secret Revealed" she greets Bloom to which Bloom replies that she is currently on break from school and starts to leave. Mitzi stops her and questions her sudden departure from Gardenia leading Bloom to explain that she had switched schools to which Mitzi rudely implies that it must be a school for slow learners. Insulted, Bloom corrects her and Mitzi still does not believe her and so Bloom snaps back and left. After the fire that was set ablaze on Vanessa's flower shop, Bloom was deemed a hero which was broadcasted on TV which Mitzi saw, she became furious at Bloom's success, bashing a pillow against her couch and walking away from her TV because she could no longer stand it.

She makes her final appearance in this season in "The Font of the Dragon Flame" and once again mocks Bloom by asking as to why she is back. Bloom, completely not in the mood to deal with her, lightly greets her and rides off. Mitzi follows her in her car and rudely asked if she was kicked out, Bloom informed her that that was not the case and it was under her own decision, Mitzi did not care and joyfully exclaimed that she had failed and rode off. A few days later, Mitzi once again pesters Bloom and assures her that she is indeed a nobody and almost ran over Kiko, Bloom has had enough and turned her scooter into a pig. Mitzi then goes and complains to the people who had delivered her scooter that the pig was really her scooter and obviously the two men did not believe her.

Season 2
In this season, she sends Bloom an invitation to her Halloween Party and allows Bloom to bring her friends along. Mitzi however, plans to prank and embarrass them at her party. She rents out a mansion that gives off a Halloween feel to it, and decorates it with the appropriate assets to make her prank believable. Then, while out on a drive with a friend, she notices the Winx walking down the streets and has her driver honk at them. She acts surprised that Bloom returned to her hometown. Bloom then introduces Mitzi to her new friends and after the introduction Mitzi reminds them that the party is at eight and to not look "so scruffy" before commanding her drive to start driving again.

The party begins and Mitzi changes into her costume before walking down the stairs in pride. She takes in the awe the people gives her before stopping, noticing that the CD player is skipping. She angrily walks down and rudely scolds the person manning the player and tells him to scram, causing him to burst into tears.

Once that was dealt with, she blandly shows appreciation for Bloom's attendance before twirling and showing off her expensive dress she had custom made for the party. She then critics Bloom and Aisha's "costumes", commenting on its disappointment and is clearly unimpressed. But when the Winx reveal their actual "costumes", she is shocked that theirs were more stunning than hers (especially since they shifted the attention to them). She is then left irate and when a friend comes to comfort her, she deviously tells her what she intends to do to them.

During the party, she takes enjoyment out of mocking, insulting and harassing the Winx. After awhile, she begins her prank. She has her maid frantically call for the Winx (while they were observing/reading all the gimmicks Mitzi placed throughout the house) into her bedroom where she is laying on her bed, acting hysterically frightened. That is when her friend tells the tale of the four sisters. It is said that the three older sisters sought revenge for the unintentional murder of their youngest sister and sold their souls to some witches. That is when Mitzi informs them that the mirrors shattered, signifying their return. Mitzi was able to convince the Winx to help and they went out to deal with it.

Once they were outside, Mitzi returns to her party, pumpkin in hand and joins in on her guests laughing at the Winx. She then silences them and has them prepare for the finale. With her friends and guests helping to spook the Winx, Mitzi gets dressed as the fourth sister and walks towards the Winx. At the climax, Mitzi presents herself to the Winx as the fourth sister but Stella immediately saw through her and calls her out. Mitzi then removes her mask irritated that Stella ruined her prank, but took out what little enjoyment she had watching them scared until the prank is backfired onto her - a "real ghost". Now, truly frightened, she faints.

And then, back at the party, the Winx start up the dance floor and having fun. Mitzi however, refused a dance because she is clearly upset that her prank failed.

Season 4
Mitzi is seen considerably more in this season. She is shocked (and possibly envious) to find that Bloom is running a successful business, Love & Pet.

When Mitzi adopts a pet from Love & Pet, she is unaware that the Wizards of the Black Circle had put a spell on that pet. She is in grave danger when her pet grows, but Brandon saves her. To thank him, she kisses him on the cheek. This angers and makes Stella jealous, causing an argument between her and Brandon which resulted in Stella ignoring Brandon for awhile. Mitzi then uses this as an opportunity to try and get close to Brandon.

Mitzi then attempts to ruin Stella and Brandon's relationship for good, but her efforts ultimately prove useless. She is always finding ways to be by Brandon. Mitzi becomes very jealous of Stella when she sees that Brandon is always with her. Mitzi still keeps trying to be with Brandon even when he and Stella reconciled.

She and her friends Sally and Darma, jealous of the popularity of the Winx and of the fact that they are fairies accept an offer from the wizards and are transformed into dark fairies who attacked the people of Gardenia, causing them to have negative feelings and to hate the Winx. Using their positive Believix powers and by helping the people there, the Winx cause the dark powers of Mitzi and her friends to weaken and disappear, turning them back into normal humans who did not remember what happened to them.

She appears one last time in this season in the episode "The Nature Rage", after the Winx had freed the imprisoned Earth Fairies, Diana came to Gardenia and allowed nature to take back what humanity took from it. Mitzi screamed for help to which the Winx responded to, only to discover that she had car trouble - her SUV, tangled up in vines. At first she told them to just go back to what they were doing, but as they started to walk away she took back what she said and asked Bloom to get it down for her. Bloom did so but left it to crash onto the ground which ruined the car and led Mitzi to freak out. When she was about to berate Bloom for it the giant spider Diana had conjured up arrived and spooked Mitzi a bit but she became completely devastated when Aisha used her car to attack the spider. She was then left speechless when the Winx teleported the spider and themselves away from the premise.

Season 5
Mitzi appears with her little sister, Macy, who is holding the Lilo, a mystical plant that has great power. Mitzi is dreading it because she has to babysit Macy. Even though Mitzi promised to take her to the Community Garden she runs her errands first (i.e. having drinks with her friends and then shopping).

Her shopping spree is interrupted by unwanted visit from the Winx. Despite fact that Mitzi never met the Trix before in the series, she is also revealed to support the Trix in capturing the Lilo, and defeating the Winx. Although she would have been satisfied to see the end her enemies, she steps in with other citizens and believed in the Winx. Effectively helping the Winx girls stop the Trix from getting the Lilo.

Season 6
In Season 6, Mitzi makes a cameo at a Gothic style party in Gardenia in "Broken Dreams", as well as in the next episode.