Kingdom Hearts Birth by Sleep
Xehanort first appeared chronologically in Kingdom Hearts Birth by Sleep at the Keyblade Graveyard when Master Xehanort used his Keyblade to unlock his heart and possess Terra after the creation of the χ-blade. He sought to use Terra's body as a younger and more powerful weapon as he ventured deeper into the mystery of the Keyblade War. Terra failed to shield himself with his armor, becoming a younger incarnation of the elderly Keyblade master. As he walked off, the possessed Terra was forced to battle Terra's discarded armor, which had come alive through Terra's mind. After the fight, Terra-Xehanort was knocked unconscious and was then sent to the Radiant Garden in a blast of light caused by the destruction of the χ-blade (and Vanitas) by Aqua and Ventus. The discarded armor continued to reside in the Keyblade Graveyard from then on, Kingdom Hearts vanishing above it.
Aqua, learning from Master Yen Sid that her friend Terra's heart had been lost, was led to Radiant Garden through Terra's voice after hearing it when she left a comatose Ventus to rest peacefully in a chamber in the newly reshaped Land of Departure. It was in the Radiant Garden that Aqua met Terra-Xehanort. Confused about his identity (due to the conflicting hearts Terra and Master Xehanort within him) Terra-Xehanort attacked Aqua with Master Xehanort's Keyblade and a Heartless-like symbiote. After the climatic battle, Terra begins to get the upper hand in his and Master Xehanort's internal struggle, which forces Terra-Xehanort to use the Keyblade to force him out. However, the symbiote drags Xehanort into the Realm of Darkness, Aqua diving in after him and sacrificing her armor and Keyblade to save Terra-Xehanort. After these events transpired, Braig took fellow apprentice Dilan as well as their master Ansem the Wise to the location of the battle between Aqua and Terra-Xehanort, where the amnesiac Keyblade wielder lay unconscious with no memory at all, except the name "Xehanort". On Ansem's order, the amnesiac young man was taken back to the castle along with Aqua's armor and Keyblade.
As the years passed, Xehanort became Ansem's leading apprentice, showing remarkable talents and having a great curiosity about the true nature of the heart. He also began to work with Braig, who would begin to construct a plan to mass produce the nefarious Heartless alongside him. Little was Xehanort aware that inside him a battle between the hearts of Terra and Master Xehanort was taking place, the two arguing over who was to control Xehanort's body.
Between Kingdom Hearts Birth by Sleep and Kingdom Hearts
Although he was confused about his past, Xehanort's quick learning and cunning made him the foremost apprentice of Ansem the Wise. Xehanort was described by Ansem as having abilities so remarkable that they could be considered supernatural. Eventually, Ansem began to worry about the darkness that lingers within the hearts of others and sought a way to stop it before it consumed his people. Ansem constructed a laboratory under his castle where he, Xehanort, and Ansem's five other assistants (Braig, Dilan, Even, Aeleus, and Ienzo) would conduct experiments on darkness.
Xehanort, who Ansem now fully trusts as an apprentice and friend, offered to use himself in the experiments. Ansem also hoped to unlock Xehanort's memories in addition to uncovering a way to repress the darkness within hearts. Xehanort had other plans in mind though and decided to conduct his own experiments to go deeper into the research.
Xehanort, Braig, Dilan, Even, Aeleus, and Ienzo carried out their own experiments where they abducted countless people and locked them within the depths of the laboratory where Xehanort then conducted horrible experiments on the subjects. After using many test subjects, one set of experiments led to the collapse of their hearts. The subjects then went into unrecoverable conditions and were locked up in the dungeon of the castle. Eventually, Xehanort checked on the subjects and saw that they transformed into creatures of darkness, which he named "The Heartless" as they apparently lacked hearts. At this point, Xehanort had taken Ansem the Wise's name as his own and wrote his own report under this stolen name.
Xehanort then presented the Heartless with living and non-living samples; the Heartless only responded to the living. Xehanort witnessed the Heartless consume the living creatures and then multiply into more Heartless. Xehanort deduced that the Heartless seek the hearts of other things, which explains why they only react to living samples, in order to create more of their kind. Xehanort and his associates soon began to slowly accept the darkness, allowing them to have limited control over the Heartless.
They in turn began to look less and less human, a factor that Ansem himself realized. When Ansem learned that his apprentices continued with the research, he called them together and ordered for them to cease their efforts immediately, all the while questioning what was happening to his loyal apprentices. Xehanort, however, saw his master as a fool who had no understanding of research and kept the research operating.
After observing the behavior of the Heartless and their responses to living things, Xehanort took one of the Heartless aside and observed its behavior. The Heartless began to move throughout the castle until a door appeared which Xehanort was, somehow, able to open. Behind the door was a humongous mass of energy to which the Heartless reacted immensely. The opening of this door led to the collapse of the world's boundaries, which was seen in the form of a meteor shower. Xehanort eventually deduced that the door actually led to the heart of that world and that the opening of this door led to the collapse of the walls between worlds.
This allowed inter-dimensional travel as all the walls between worlds were now broken and eventually a visitor showed up named King Mickey. He had constructed a Gummi Ship, a spacecraft capable of breaking through world boundaries, out of materials from the meteors and used it to visit many different places in search of answers of recent events. Xehanort and Mickey met and had huge discussions in which Xehanort learned of the Keyblade, a mysterious weapon that Mickey himself possessed.
There were also legends that told of seven princesses with pure hearts and how they have a connection to this Keyblade. The Keyblade can also be wielded by many, as long as their hearts qualify, and it seems there is a legend of one Keyblade bearer who went on a journey of destiny to seal off the doors to other worlds. Since this was not in Xehanort's interest, he sought a way to find this weapon, which is ironic, given that his former self once wielded one, but was now lost. Mickey eventually met and befriended Ansem the Wise and the two of them exchanged theories and ideas in his office about what the Heartless were after. Ansem decided to resist the urge to test their theories while expressing deep remorse for his actions.
However, Ansem had no idea that Xehanort had gone further than he himself even dared. Xehanort entered the office during their discussion, asking Ansem's permission to test an experiment. Ansem forbade Xehanort to conduct it and told him to forget everything he learned from the research.
Even though Ansem had no further urge to research the darkness, the experiments led by Xehanort continued including the creation of a machine that created artificial Heartless, all of which were marked with an emblem created by Xehanort in order to differentiate them from the pure-bred Heartless. King Mickey suspected something odd about Xehanort and told Ansem to check his lab, collect all his data, and see if everything was under control.
Ansem did so and learned that Xehanort had taken his name as his own and wrote a detailed report. From the report, Ansem learned of the horrible torture inflicted on people by the inhumane experiments that Xehanort had done. Ansem ordered his apprentices to seal off the laboratory and cease their scheme for knowledge.
Ansem's apprentices did as he instructed them but Xehanort eventually banished Ansem to the Realm of Nothingness and ravaged the world with Heartless. The Heartless under the command of Xehanort began spreading to other worlds and destroyed numerous ones in their mad search for hearts. One side effect of the destruction of so many worlds was the creation of Traverse Town, made up of the remains of the ruined worlds and populated by the few survivors of those said worlds. Xehanort then ordered for the seal on the laboratory to be broken and that a room that he called the "Chamber of Repose" be constructed. Once done, Xehanort often went in and spoke as if there was someone else in the room. It is later revealed that the room housed Aqua's armor, which Xehanort used to help gain further recollection about his past.
Xehanort then abducted and sent Kairi, a resident of Radiant Garden, to the oceans of other worlds. The reason for this was because Xehanort thought Kairi had a connection to the Keyblade bearer, as she seemed to possess power comparable to that of a Princess of Heart, which is rumored to posses a connection to the Keyblade. He hoped to use her to find the Keyblade master and prevent him from sealing off the doors to other worlds.
Xehanort made the final pages of his report, which outlined his intentions as well as those of the Heartless. The Heartless seek to consume the hearts of all living things. However, they not only seek human hearts, but the hearts of the worlds themselves. Their ultimate goal is to collect enough hearts to form the biggest heart of all, the heart in which all that exist are evolved from: Kingdom Hearts. Xehanort decided to use the Heartless' instincts to make his own plans.
He would find Kingdom Hearts in order to gain ultimate power, control, and knowledge. Xehanort also learned that the creation of a Heartless can also lead to the creation of another creature called a Nobody, beings that are left over bodies of those whose hearts have been stolen away. They transform into an inhuman state and do not truly exist as they lack a heart to make them truly live.
Xehanort and the others eventually gave themselves to the darkness to gain the ability to control all Heartless and wield the powers of darkness. They lost their hearts in the process and they became powerful Nobodies. However, Xehanort was the only one to have both a human Heartless and a human Nobody, both possessing the memories and personality traits prior to their creations. Since they possessed strong hearts, Xehanort and his followers (Braig, Dilan, Even, Aeleus, and Ienzo) were able to retain their human forms as Nobodies. Radiant Garden was almost completely destroyed, save for the castle and the mutated waterways, which had several modifications done to it by Xehanort and the other apprentices, and most of its people were wiped out while some (like Leon, Aerith, Yuffie, Cid, and Merlin) managed to escape to Traverse Town.
Kingdom Hearts II
While Sora was investigating Ansem the Wise's study within Hollow Bastion, he spots a portrait of an unnamed man. He and his friends (Donald Duck and Goofy) realize that this man was the original being of "Ansem", who Sora had defeated one year ago. After speaking with Tron and learning more about Ansem the Wise, they return to Ansem's study and run into King Mickey, who indicates that the true Ansem was not the one they fought. He asks them to give Tron some further help, and once they return, they find an image of an unknown man on Tron's computer, which Mickey identifies as a picture of the real Ansem. Later, after defeating the Heartless swarming the town, the trio encounter Xemnas, the Nobody of the fake Ansem and the superior of Organization XIII. Mickey finally remembers that Xemnas's original being was Xehanort, and explains about his past encounter with Ansem and Xehanort.
In The World That Never Was, King Mickey encounters the true Ansem, and learns from him that his goal is to destroy Xemnas's artificial Kingdom Hearts and exact revenge on Xehanort for stealing his name and pride. Riku and Sora also refer to the fake Ansem as "Xehanort's Heartless", when Sora mistakes Riku for the villain, and when Riku explains how he had gained Ansem's form. Later on, Ansem repeatedly uses the name "Xehanort" to insultingly refer to Xemnas, who replies by listing Ansem's own sins, and accusing Ansem of always holding his research back. Xemnas's demise at the hands of Sora and Riku apparently ends the threat of Organization XIII, yet also paves way for Xehanort's eventual return.
With Master Xehanort's impending return drawing closer and closer, Yen Sid finally reveals the truth behind Xehanort to Sora and Riku as he tasks them with the mission to awaken seven different worlds from a state of sleep. However, as Sora and Riku go through these worlds, they are intercepted by various incarnations of Xehanort, including Xehanort's Heartless, Xemnas, and a younger version of the Keyblade Master. It is eventually revealed by Braig, who has also returned due to his Heartless and Nobody being defeated, that Master Xehanort has enlisted the help of his younger self from an alternate timeline, who was given powers to survey time and space itself to enlist different incarnations of himself, including Xehanort's Heartless and Xemnas, to form a new Organization XIII. With these various forms of himself under his control, Xehanort uses them to draw Sora deeper into the worlds of sleep to use him as a vessel to complete the new Organization. Riku and Mickey are able to locate a comatose Sora in the Organization's former headquarters and face Xehanort's younger self in battle to save him. When they defeat him, Master Xehanort finally returns to full power.
Upon Master Xehanort's return, the villain reveals that he has not given up on his plans to form the χ-Blade and incite another Keyblade War. In fact, he further states that everything that has occurred throughout the past two years, from Maleficent capturing the Princesses of Heart, to the formation of Organization XIII, was all part of an insidious, fail-safe plot to form the χ-Blade. Xehanort explains to Riku and King Mickey how his plans to merge Ventus and Vanitas were an overly hasty attempt to form the χ-Blade, and that he overlooked the true way to create the weapon; by clashing thirteen hearts of darkness against the seven defending lights of the worlds. It is revealed that in the aftermath of the Keyblade War, the χ-Blade was shattered, and released seven lights and thirteen darkness's, and when the two sets of light and darkness were brought together, the true χ-Blade would return.
Over a decade ago, Xehanort enlisted the help of Braig, who desired the power of the Keyblade for himself, to form Organization XIII, gather thirteen strong beings to fill with fragments of darkness and Xehanort's heart to make them all clones of him, and use them to fight the seven Keyblade defenders of the worlds to recreate the χ-Blade. Braig was the first of these planned clones, which was why his appearance changed—he had a yellow eye and pointed ears—due to him agreeing with Xehanort's plans; he would be able to share in Xehanort's power and wield the Keyblade once a full clone, though he would slowly lose his will and mind to Xehanort, in exchange. To further these plans, Xehanort, possessing Terra's body, and Braig enlisted the help of Ansem the Wise's other apprentices and exploited his research to experiment with separating hearts from bodies in order to create Nobodies of them all, leaving them hallow vessels ready to be filled with fragments of Xehanort's heart, as well as build up a destructive force of Heartless for their plans. However, as Xehanort himself also separated his heart and body, his Nobody, Xemnas, made plans to form an artificial Kingdom Hearts in order to gain the power to fragment his heart into the other Nobodies.
However, Xemnas and Braig knew through their research of Heartless and Nobodies that Nobodies could indeed cultivate hearts once more and develop emotions, as with the case of Roxas, Namine, and Axel. Knowing that this would entice the members of the Organization to disobey them, Xemnas and Braig deceived them all by telling them that Kingdom Hearts was the only way to recover their hearts. However, most of the members were either too weak or turned traitorous before they could be turned into appropriate vessels, and had to be eliminated or were defeated by Sora and Riku. Xigbar, the Nobody of Braig, and Saix, the Nobody of Isa, were the only members that were strong enough and had gone through the initial stages of the cloning process. Xemnas, however, knew his younger self was assembling a fail safe group and continued on his plans to form Kingdom Hearts to gain absolute power, and embark on the next phase of his plans.
At the same time, Xehanort's Heartless destroyed thousands of worlds to form a Kingdom Hearts made entirely of darkness, and manipulated Maleficent into capturing the Princesses of Heart to use their hearts to locate the Door to Darkness in an attempt to extinguish their light and leave the worlds vulnerable to the darkness. However, this plan was promptly thwarted when Sora rescued the princesses and began destroying the members of Organization XIII, but Xehanort took precautions in case of such circumstances. To this end, Xehanort's Heartless enlisted the aid of a younger version of himself from a separate timeline, and gave him the powers to survey time and space itself in order to enlist 6 different incarnations of himself, while Braig and Isa rejoined Master Xehanort, to create a new Organization XIII. Riku was originally intended to become the final vessel once Xehanort's Heartless seized complete control of his body, but this failed when the heartless was destroyed and Riku built up a tolerance to the darkness. Xehanort then moved his sights to the next best candidate—Sora.
Once this new Organization was formed, Master Xehanort intended to use them to eliminate the Princesses of Heart, thus throwing the worlds into turmoil and leaving them vulnerable to the darkness. Then, by having the thirteen members of darkness clash with the seven lights, the χ-Blade would finally be forged, the true Kingdom Hearts would resurface, finally complete, and the Keyblade War would begin anew. Through this war, Xehanort would finally gain all the answers he craved for most of his life, and become all knowing. Through the great darkness that would awaken, Xehanort would reorganize the worlds to one where light and darkness are balanced, in a universe under his rule. Xehanort then attempted to make Sora his final vessel, but was stopped by Lea. Xehanort then sent his Heartless and Nobody counterparts to defeat Riku, Mickey, and Lea, but they were defeated with the timely arrival of Donald and Goofy. Unshaken by this minor setback, Xehanort informed all the heroes that the clash between light and dark is inevitable and bids them farewell as he looks forward to the start of the battles that will create the χ-Blade and escapes.
In the end, Yen Sid and Mickey prepare to form a group of seven Keyblade Wielders of light to stop Xehanort and his new army from murdering the Princesses of Heart and forging the χ-Blade to start a second Keyblade War, while fearing that such a war may be inevitable, as the seven lights and thirteen darkness' may be forced into conflict to prevent the deaths of the princesses.
Role in the series
Xehanort is the real Big Bad behind Mirage and Cobra's schemes.
Now, Xehanort will fully appear in the Spongebob and Friends Series once Yin Sid predicts that he will meet Spyro in the end of Spongebob, Alex and Friends Return to Neverland. In Spirited Away after Kairi defeats Teen Mang in the Throne Room of the Castle in the World that Never Was, the fully revived Master Xehanort appears with Cobra, Mirage and the other villains just as Mickey, Twilight Sparkle, Spike and The Louge arrive on the scene. Master Xehanort explains his past endeavors to the Shell Louge Squad and how Cobra was invovled in them, his failed attempt to create the χ-blade and reveals what will become of the Louge once Malefor and the Darkspawn Return. He also reveals that the Villain leage's Organization XIII were apart of Malefor's plan to create thirteen darknesses to clash against fourteen lights and the soul of a pure hearted misfit (Spongebob) will completely forge the χ-blade. With the louge restrained by the villains and Spongebob captrued by Myotismon, Mirage prepares to kill him while Master Xehanort prepares to place the last fragment of his heart inside Spyro, but Lea arrives on the scene and protects Spyro while Haku rescues Spongebob in his dragon form. Xigbar asks Xehanort to do somthing but Dr. Facilier retaliates by setting one of the Organization's members on Lea, who turns out to be Saïx himself while Maleficent battles her son in her dragon form. After the climax when Alex and Gia save Kairi's life by subduing the Jabberwocky, Master Xehanort retreats with the Villain Leage and their Organization but dares the louge to face him once the Fourteen Lights and Thirteen Darknesses are complete. He will make his appearence in future moisodes soon after. However, it appears Xehonort by this time is now no longer interested in making another Clash. He is not even truely loyal to Malefor, or the leage's beliefs. He and his clones are aware of the true events that'll happen in The Book of Predictions, where it'll be Mirage that dies, destroying the link between the banish realms and the united univereses forever, Mang will betray the leage, Spongebob, Kairi, and Spyro will be fine after all, there will be no X-blade, and Xehonort and his follwers false Ansem, Xemnas, and his younger clone will persue "The great Cycle", where they bring the end of the united universes, to create a new one in their image. However, even when so dark overlordly powerful, all good things must come to an end. The Lougers will eventally defeat all of his allies, reach the recreated World that never was, and eventally, fight Xehanort himself. Before his deathly defeat, he reads into the Book of Predictions one last time, and his fears were comfirmed, his desten, ineditable defeat was there in pcitures. Xehanort, started to laugh maniacly, knowing that, at least, he was able to enjoy his insanity while it lasted, as he is sent to darkness through his end, and turning everything to normal.