The Trix are the descendants of the Three Ancient Witches who destroyed Bloom's home planet, Domino. They have served Lord Darkar and also freed Valtor from the Omega Dimension. They are former students of Cloud Tower.
The Trix call each other "sisters" or "little sister" and it is assumed that they are indeed really biological sisters, as the concept of witch covens was never mentioned in the series. In Hallowinx!, Bloom suspects the "three sisters," to be the Trix, therefore acknowledging them as siblings. In Twinning With The Witches, Miss Griffin tells the Winx that Witches never work in groups as they always tend to betray each other, thus ruling out the possibility of Witch covens existing in the Winx Club universe. Despite this, they use a convergence at one point. Considering the unusual solidarity among them, the fact that all three of them claim descent from the Ancestral Witches, and that they - along with the Ancestral Witches - are the only Witches known to have worked in groups, it is assumed that they are indeed biological sisters. This is confirmed in The Problems of Love when Stormy yells, "We're your sisters!"
Story in Winx ClubEdit
At first, they sought for Stella's ring until they realized it did not contain what they were looking for. For most of the first season, the Trix seemed to be more powerful than the Winx Club (with the exception of Bloom), as seen in the episode Betrayed! where they were able to get the better of the fight, and would have won had Bloom not intervened. In this event, they discovered Bloom's incredible power and got Riven to spy on the Winx. For most of the first season, they attended the Cloud Tower School for Witches until they got expelled. Soon after, the Trix stole the Dragon Flame and summoned the Army of Darkness to take over the realm of Magix. In the end, they were defeated and taken to Lightrock Monastery.
In the second season the, Trix became the servers of the infamous Lord Darkar who freed them from the Fortress of Light Monastery and gave them the power of the Gloomix which made them stronger.
They helped him obtain 3 out of the 4 pieces of the Codex, and fought against the Winx and the Specialists numerous times for his sake. When Darkar turned Bloom into Dark Bloom after kidnapping her, the Winx and Specialists came to her rescue and the Trix used their Gloomix to make Darkar's evil creatures more powerful, draining themselves of all their magic.
Exhausted, the Trix went to Darkar when he was about to enter the Realm of Realix with Dark Bloom so as to seek the Ultimate Power. When the Trix told him they had done all the dirty work for him and expected a share of the Ultimate Power as a reward, hoping that they had not been just his pawns, Darkar attacked them, telling them that they had effectively been mere pawns in his game and banished them into the Realm of Oblivion.
There, the Trix fused into a single body and entered Realix to have their revenge on Darkar and they fought him. They quickly became tempted by the Ultimate Power that Dark Bloom was summoning and while going towards Bloom to acquire it, Darkar attacked them, knocking them out. After Darkar was defeated, they remained imprisoned in the Realm of Realix and some time later they were captured, frozen and sent to the Omega Dimension where they met Valtor.
In the third season, they joined Valtor, to aid him in his plans. The three witches competed for his affections and his power, before finally leaving him when he assumed his demon-like form and lost all the spells he had stolen. They also grew younger in The Black Willow's Tears, because of the special water in Linphea after unintentionally helping Flora gain her Enchantix and turned into young girls. For most of the season they were over-powered by the fairies' Enchantix. In Witches' Revelation, they acquired the Disenchantix from Valtor, but still lost to the Winx. At the end of the Season, they are captured again by the Knight-monks of the Fortress of Light, who tell the Winx that they will meet the Trix again one day.
Winx Club: The Secret of the Lost KingdomEdit
Towards the end of the first movie, the Trix's bodies are seen being possessed by the Ancestral Witches, which is most likely to be a prelude to the events in the second movie, where the Trix work under the influence of the Ancestral Witches.
They returned again in the second movie, where they sneak into Alfea during the beginning of year festivities, putting a spell on all the food there so that everyone who ate some of it was turned into a toad, and stealing a magical compass which they used to lead the Ancestral Witches to the Tree of Life found in the Pixie Village. The Ancestress proceeded to absorb all the essence of Good from the Tree, causing all good magic to disappear, and only dark magic to keep on existing. At the end of the movie, the Winx Club, the Specialists, Oritel and Erendor arrive at the haunted city of Havram to find the sapling of the Tree of Life which the Ancestress gave to the king of Eraklyon as part of the deal which forced him to betray the promise he made to Oritel (that he would protect Domino against the Ancestress) by allowing the three Ancient Witches to destroy Domino in exchange for their sparing Eraklyon. There, the Trix and their Ancestress were waiting for them, but the Winx Club girls gained back their powers and Bloom's horse, Peg, became a flying unicorn thanks to the magical sapling, which restored all the Good Magic of the Magic Dimension after being hit by an attack of Icy initially aimed at Bloom. Finding the Trix to be ineffective as vessels to defeat the Winx Club and as punishment for releasing the Good Magic, the Ancestral Witches try to possess the Trix, but as they attempt to flee the old witches capture them and possess their bodies. The Trix, now possessed by their ancestors, have become more powerful than ever, as well as mere puppets possessed by the Ancestral Witches. The Winx, the Specialists, Oritel and Erendor take part in the battle, but Erendor is severely wounded trying to save Bloom from Icy - Belladona. Finally, using a Believix convergence, the Winx Club are able to summon the essence of the Great Dragon and extract the Ancestral Witches from the bodies of the Trix. The Dragon Flame power destroys the Ancestral Witches for good, and the Trix, defeated, fall unconscious to the ground. Helia ties them with a rope and, as the movie ends, they are shown as being suspended from the flying ship the Winx, the Specialists, Oritel and Erendor use to leave Havram, getting angry as Bloom and her friends fly around them and tease them.
As we all know, they were sent to prison and stayed there at the end of Season 3. In Season 5, it is revealed that the Trix had been sent to the prison of Andros, being troublemakers in Magix, where they meet Tritannus, who Icy falls madly in love. Together, they escape from prison after Tritannus transformed into a monster by absorbing pollution from an explosion on an oil rig on Earth that spread through an ocean portal from Earth, to his prison cell on Andros. Because of the power Tritannus has, he shared it with the Trix. In exchange, the Trix help Tritannus to gain more power by absorbing more toxic. They control the mind of humans to throw toxic wastes into the ocean. In The Rise of Tritannus, they go to Earth for the first time since Season 1. Later on, they noticed that there was something in the air; they realized that it is Magic, Fairy Magic. So Tritannus sends his mutants to find and destroy the fairies. This was the first time that the Trix fought the Winx in the Season. Later in the battle, Icy calls Tritannus for help, who responds by hitting, Bloom, Stella, and Musa from below, showing concern for Icy.
Flora, Aisha and Tecna swim underwater to see who is in there. But then Aisha realized that it was her cousin, Tritannus, the son of King Neptune. The Trix then manage to defeat the Winx In their Believix form with the help of Tritannus. The Trix again showed up and battled with the Winx in the Magic Archives of Alfea when the Winx was looking for the Sirenix Book. Icy hits Sky in the battle and runs away when Griselda and Faragonda showed up in the room. Together, the Trix again fought the Winx unsuccessfully because their Harmonix were too strong for the Trix. Meanwhile the love between Icy and Tritannus grew and it made Darcy and Stormy jealous because they felt that Icy cared more about Tritannus than about them.
Later Tritannus stole Daphne's Sirenix and gave it to the Trix, and they entered the Infinite Ocean where Tritannus tried to activate the Emperor's Throne but failed and had to refuel his toxic powers on Earth with the help of the Trix after which there was a fight between the Winx and the Trix and the Trix and Tritannus fled into the Infinite Ocean where, to their surprise, the Winx followed them but thy were able to run away because Tritannus told Aisha that to destroy him and the Trix she will have to destroy her mutated family, Neptune, Ligea, Nereus, Tressa, first. Tritannus then decided to steal the seals of the Pillars of the Infinite Ocean to repair the Emperor's Throne when he found out that he could not activate it was because it was broken. However when he attacked the Pillar of Light Darcy and Stormy started feeling that Icy and Tritannus did not care for them, and then after a fight with the Winx Tritannus, Icy and the mutants ran away without Darcy and Stormy, making them feel frustrated. In the fight Icy protected Tritannus by taking an attack by Bloom that was aimed at him and Tritannus then vowed to Icy that he will destroy the whole Magic Dimension by attacking all the Pillars. While Tritannus was gathering the seals and Icy getting excited about becoming an empress, Darcy and Stormy felt like they didnt even notice them anymore. When Tritannus failed to get the final seal before Winx destroyed it, Darcy and Stormy leaves Tritannus for good. They later appear to absord Politeas powers right front of Icy, who wanted them in the first place. Tritannus captures Aisha and uses her to power up the Emperors Throne, only to get possessed by the power itself. He attacks Icy who is protected by Darcy and Stormy. When they try to strike Tritannus, he sends them flying away. Their current fate and location is unknown but it is possible they are alive.
Against the TeamEdit
When Sora recruited the Winx Club, the Trix wanted to take the opportunity to destroy ALL of the heroes but then after their battle with the team, they were no match for Sora and the Keyblade. Then they joined Maleficent to gain more power for themselves and getting ridd if the fairies.