Mylene Farrow was the Aquos Brawler of the Vexos, who used Elico and Macubass as her Guardians and Tripod Theta as her Trap.
Mylene is first shown in Invasion of the Vestals with the other members of the Vexos, watching as all the Bakugan are captured.
In Get Psyched, she appears watching Shadow Prove's match with Baron Leltoy, insulting him after his loss and complaining about his bad piloting.
In Marucho's Mission, she battled Marucho Marukura and almost won because of her Bakugan TrapTripod Theta, which used after her Abis Omega, Clawcer and Stug. She then battled Shun Kazami and lost, which was off screen.
Prince Hydron gives her control over the Vexos. She quickly formulates a strategy, by separating the three remaining members of the Resistance and then taking them on one by one. To do that, she has Shadow imitate the voice of Dan Kuso and Mira Fermin to lure Marucho Marukura and Ace Grit. Only Shun realized that it was a trap, but it was too late for the other two members. Mylene then faced off against Ace, defeating him with her new attribute-changing Bakugan, Elico. With her last attack, Ace fell into the water, but could not swim back up. With that, she claimed that "Their nightmare is just beginning."
In Beta City Blues, she battled Baron Leltoy and Dan Kuso in Beta City alongside Shadow Prove but was defeated, and the Dimension Controller was destroyed. She then battles with Shadow again in Gamma City this time against Marucho Marukura and Shun Kazami and still lost the battle to them.
In Saved By the Siren, After Prince Hydron defeated Baron and claimed the Haos energy, she went to retrieve the Darkus energy out of jealousy with her new mechanical Bakugan, Macubass. She would have most likely defeated Ace Grit, but Klaus showed up and helped him to win the battle while remarking that she is indeed beautiful.
In Earth Invaders, she and Lync Volan went to Earth, and as Mylene stood out in what she was wearing, she tried to find a suitable disguise but ended up sticking out more when her disguise of choice was a white tuxedo for a groom, then they battled Runo Misaki and Mira Fermin and won, taking the Subterra attribute Energy in the process.
In Virtual Insanity, she and Shadow go back to Earth in search of one of the three Attribute Energies left. They track Billy Gilbert through his gauntlet and follow him to Marucho's house and now know where the Brawlers are hiding. Later when the Brawlers are in the Vexos Motherpalace Mylene, and Volt Luster battle Shun and Baron and they defeat both Brawlers and take the Ventus Attribute Energy.
In Volt's Revolt, Mylene and Volt Luster both show disapproval of Professor Clay's actions. However, Mylene chooses to stay and warns Volt that he'll "Have to look over his shoulder all the time." She wishes him luck after he leaves and calls him "my friend." Later, when Prince Hydron reveals he "took care of Volt" she appeared to be saddened.
In Payback Mylene was ordered by Zenoheld to get the data from the brawlers they need for the Alternative. She later confronted Lync when she told him that they're about to infiltrate the brawlers' base. Lync claimed that He was helping Professor Clay with the Alternative. Mylene, however, feels something suspicious going on. Soon after that, Mylene entered Professor Clay's lab to test Lync's claims about assisting Clay. Then she overhears from Clay that someone made the copy of the Alternative date, and says it was Lync. She tries to find Lync, but he already teleported to Earth before she can catch up to him. Then she reported to Zenoheld about Lync's actions. At the end of the episode, Mylene was seen along with the remaining members of the Vexos after Hydron punished Lync for his betrayal.
In Mylene's Meltdown, she and Shadow infiltrated the brawlers' base to get the data they need for the Alternative Weapon. She reveals that she is now a free agent as she figured that she could not depend on anyone but herself anymore. After capturing Mira Fermin, she and Shadow Prove are led to Bakugan Interspace by Keith Fermin after he tricked them into thinking he was leading them to the Phantom Data. She laments on how weak Spectra Phantom has become, and he tries to get her to learn the importance of teamwork. After they were transported, she brawled against Spectra and Mira in Marucho Marukura's Bakugan Interspace along with Shadow once again and lost. After the battle, Spectra tried to reason with her and offered her and Shadow into the Resistance which Mira unconditionally agreed to. However, Mylene refused, and she tried to send the Clay siblings to another dimension, but the Bakugan Interspace shut down, and everyone became trapped in it.
In An Heir To Spare, she tries to kill Spectra and his sister Mira Fermin with her Aquos Gauntlet sword, but Keith is able to hold her at bay until Bakugan Interspace started to collapse and Mylene was being sucked in as a result of her setting off a death bomb to banish the Clay siblings. Keithand Mira tried to save her, but she said she would rather die than accept their help. The ground then collapsed under them causing Mylene to slip from them and get pulled in. However, shortly before she was sucked in Shadow pulled her hand and was pulled in along with her. After they were sucked in, Mylene said "that was a really stupid thing to do," to which Shadow Prove replied, "I thought it would be way more fun to travel to the ends of the dimension with my new best friend." Mylene was shocked, possibly because she knew Shadow truly cared for her, and smiled back at him. They were last seen in some dimension still holding on to each other's hand before disappearing.
And she will be voiced by Elizabeth Maxwell in the English dub and reprised by Fuko Saito in the Japanese dub.