About 100,000 years ago before the start of the series, Makuta Teridax was brought into being by the Great Beings using the substance known as the Antidermis on the island in one of the southern chains of the Matoran Universe.
Later when Miserix founded the Brotherhood of Makuta, he was appointed as the lieutenant of the army of the Brotherhood, who was tasked with maintaining order in the universe and serving the Great Spirit's will. Like all the other Makuta, he was also fulfilling the goal by creating various Rahi to populate the planet as he created various breeds of Rahi, including the Water Wraith, Rahi Nui, etc. Later, Teridax then became the most trusted lieutenant of Miserix, whom he respected.
When Mata Nui and his organization called the Order of Mata Nui came into being, he encountered him and soon, they eventually became both the best friends and brothers as they worked together to protect the universe from many threats.
When Miserix learnt that the Vortixx had charged the price of the trade with the Matoran, he sent Teridax to ask Mutran, the Brotherhood's scientist to accompany both Icarax and his aide Pridak to travel to Xia to negotiate with the Vortixx to lower the price.
When Pridak left the service of the Brotherhood and formed the League of Six Kingdoms, Teridax hired Takadox to act as a spy for the Brotherhood. He and Icarax later attended a meeting with Kalmah and Ehlek, two members of the Barraki as they came to Destral and demanded that the Brotherhood continue to provide Rahi and anything else they ask for. When Teridax returned to report to Miserix, the latter then ordered his most trusted lieutenant to keep watch on the Barraki.
When the League of Six Kingdoms attack the island of Metru Nu in an attempt to overthrow the Great Spirit, Teridax was ordered to assemble the Brotherhood's army and dispatched to Metru Nui as they were also joined by the alliance of the Toa and the Order of Mata Nui.
The Brotherhood's Corruption
About a few days later after the Matoran Civil War, Miserix assigned all the members to protect various regions across the universe as Teridax was assigned to protect Metru Nui as the reward of stopping the war.
Unfortunately, Teridax eventually became very jealous towards Mata Nui when he realised that his friend and brother gained all the praises from the Matoran. To make matters worse, he was also influenced by the Barraki's in
The Mask of LightFollowing the defeat of the Bohrok-Kal , the Kanohi Avohkii, known as the Mask of Light was eventually discovered by Takua in the lava chamber during his Kolhii training with his friend Jaller, a Ta-Matoran and the future Toa Inika. At the same time in Mangaia, Teridax also foresaw the discovery of the Avohkii and the coming of the seventh Toa. Fearing that his darkness will disappear, he immediately extract out the Kraata from his body and fit them into armors of Guurahk, Lerahk and Panrahk, thus awakening them. Teridax then ordered them to find the Herald of the seventh Toa and destroy the Avohkii in order to prevent the prophecy from happening. The three Rahkshi then make their way to Ta-Koro where they destroyed the entire village, only to find both the herald and the mask weren't there.
Quest in Voya Nui
After Teridax's defeat, a skakdi group or renegade Dark Hunters who called themselves Piraka, heard about the Makuta's supposed demise, and searched for his lair in hopes of looting whatever left that was valuable.Zaktan already knew, unlike the rest, that Teridax was still alive in his own essence of antidermis, and used his telekinetic powers to reveal the location of the Mask of Life to the Piraka, in Voya Nui. Zaktan made all the preparatives for his overlooking ally, and after they arrived in the island, revealing themselves as Toa, and enslaved the matoran population, the first mandatory was to make a crystall recipe for Teridax, who gave part of his essence to the Piraka in form of green spheres, which were called Zamor Sphearsm,should they be launched, this spheres would physically drain all individuallity in a Matoran, but they were useless against Toa and were particularly benefactory for the Toa Inika and for Brutaka's species. During the events in Voya Nui, Teridax was just a spectator; comunicating only with Zaktan and providing him more Zamor spheres, until one battle with Axxon and Brutaka broke his crystall receptacle, and he came with the next step of his plan, entering into Mahri Nui and abandoning the Piraka to their fate.
Quest in Mahri NuiOnce inside the black water in Mahri Nui, Teridax's essence crossed the ocean and eventually stumbled upon the body of Maxilos robot lying on the seabed. He then took control of its body and was then contacted by Gorast, who was relieved of his survival before informing him that the Brotherhood of Makuta had found the location of Karda Nui. He ordered her to inform Icarax to gather all the powerful Makuta and their army to invade Karda Nui and transform as many Av-Matoran as possible into the Shadow Matoran. Later, he traveled towards the Pit where he confronted Matoro, who was captured by the second Hydraxon as he revealed his identity to the Toa Mahri of Ice before freeing him from the cell. They then made an uneasy alliance to find the Kanohi Ignika. They make their move just before they are confronted by the Barraki's army of Zyglak and Takea sharks as the two attacked the army. Teridax chose to hide behind the rock while Matoro faced the Zyglak using the Kanohi Tryna as the Makuta did not want the Barraki to recognize him.
After the battle, Teridax and Matoro later discovered the fragments of the Staff of Artahka as the former then used the power to restore the staff. Teridax then planned to use the Staff of Artahka to restore the Nui Stone. He then began to activate the staff's power but when Matoro tries to stop him, he froze him in one of his stasis fields. Before Teridax could proceed, however, he was stopped by a mutated Brutaka. During the fight, Brutaka successfully knocked the staff off from Teridax as the staff flowed towards the open water, thus ruining Teridax's plan. Brutaka told Matoro to return to the other Toa Mahri and Matoro did, trusting Brutaka over Teridax.
Mata Nui's Reawakening
As the Brotherhood of Makuta began their invasion on the universe, Teridax traveled to Metru Nui, where he accessed to the Core Processor, located beneath the Coliseum by slipping through the made cracks in the Coliseum's foundation.
He eventually reached his planned destination, which was the former location of Mata Nui's spirit. Before Mata Nui's spirit could return to this location, Teridax arrived and took over the Great Spirit Robot. Believing that the other Makuta will challenge by the time he become the Great Spirit, he then planned to get all of them eliminated in the war.
While Teridax waited the Great Spirit's body to be awaken
Reign of Shadows
A weeks after Teridax successfully take over the Great Spirit Robot and finally taken over the Matoran Universe, the Toa and their allies were forced to hide in the tunnels of the Archives when Teridax summoned the army of Rahkshi
While contemplating his potential to conquer the rest of the universe, Teridax rememberd Mata Nui, trapped in the Ignika as it flew through the universe, and considering finding and crushing his former friend and brother. He then called to the Red Star and departed for the planet called Spherus Magna to kill Mata Nui once and for all.After the few days, Teridax arrived on Spherus Magna and sent Nektann, escorted by the few Rahkshi of Heat Vision to find the new allies. While he began his search for Mata Nui, Nektann and their allies traveled to the Black Spike Mountains, where they confronted Stronius, the general of the Rock Tribe and the Skrall as they offered them to conquer the entire universe in exchange of conquering Spherus Magna as Stronius agreed and form the alliance of their two armies.
Final Battle and Death
The Uniters somehow managed to locate Teridax in the Leva Bay of Po-Koro as they engaged him in the battle again. This time, the Uniters decide to remove the mask from Teridax, though the latter at first knocked them off. While the other five distracted Teridax with their attacks, Tahu jumped onto the Makuta and the struggle begins as the Toa of Fire try to pull the mask off from his face. As Tahu was nearly succeeded on removing the mask, Teridax somehow grab him and toss him to the other Uniters. However, the Toa Uniters were able to destroy the Mask of Power (and Teridax's spirit as well), thus killing him once and for all.