Xion is the fourteenth member of Organization XIII, first appearing in the game Kingdom Hearts 358/2 Days, in which she could be viewed as both a protagonist and antagonist. She is not actually a Nobody, and not even considered a true member of the Organization. Because of this she does not have a throne, nor does she have a title or a breed of Nobody to control. Instead, she's an imperfect Replica of Roxas created from Sora's leaked memories as a fail-safe in case both Sora and Roxas proved to be useless to Organization XIII's plans. While this enables her to use the Keyblade, Xion's existence also halts Sora's progression of regaining his memories to fully awaken while in his pod, something which Naminé, DiZ, and Riku recognize. As Sora's memories are the basis of her being, Xion initially resembles Kairi, who was Sora's strongest memory at the time of her birth, though her physical appearance eventually changes depending on who is viewing her and who they have connections with. Roxas, Axel, and Riku see her as Xion (and later as Sora), while Xemnas and Xigbar see her as Ventus, and Saix sees her only the hooded doll she started out as. Xion's name contains the Japanese words for "tide", fitting the oceanic naming theme of Kairi and Naminé, and Aster tataricus. According to Japanese floriography, Aster tataricus is used to mean "I won't forget you" or "remembrance". It is also revealed within the Secret Reports that her "original name" was "No.i", her ID as an experiment of the Replica Program. The "i" used here is in fact the imaginary number. She finally managed to regain her life back and became part of Sora's team.
Kingdom Hearts 358/2 DaysEdit
A week after Roxas joins Organization XIII, Xemnas introduces Xion to the other members. After looking at the other members, she smiles up at Roxas, puzzling him. As Roxas departs for his first training mission, he spots Xion shyly watching him nearby, and Saïx formally introduces her to Axel and Roxas.
When Axel is sent to Castle Oblivion, Xemnas entrusts Roxas with the task of looking after Xion, who quickly bonds with him. She reveals her ability to wield the Keyblade to him, and looks after him when he falls into a coma for several weeks in conjunction to Sora being put to sleep to regain his memories. After discovering that Sora and Riku had slain all of the Organization members (except Axel) that were in Castle Oblivion at the time, Roxas, Axel, and Xion all begin spending more time together as per Roxas's suggestion and become fast friends, such as enjoying Sea-salt ice cream together. After Xion asks Axel to be her friend, and he accepts, he stops seeing her as a doll, and begins seeing her as the black-haired girl that Roxas sees.
However, a series of events begin to split the trio apart: While DiZ and Naminé oversee the restoration of the sleeping Sora's memories (moving him from Castle Oblivion to Twilight Town), Roxas begins to experience the process for himself, and begins to ponder over how he is able to wield the Keyblade and doubt the Organization's motives; Axel is reprimanded by their superiors for placing his friendship with Roxas and Xion before the Organization's goals; and Xion is thrown into disarray after a confrontation with Riku, who questions who she is and why she wields the Keyblade, causing her to become torn between staying with her friends and leaving the Organization to merge with her true self as Riku suggests.
Xion travels with Riku for several days before being captured by Axel and brought back into the Organization. However Naminé's attempts to restore Sora's memories are soon halted when Xion starts absorbing them faster, causing Roxas to weaken while she becomes stronger, as Xemnas intended. Eventually, after being tricked into fighting Roxas by Saïx, Xion decides to take Riku's advice and leaves the Organization.
After her departure, Xion comes into contact with Naminé at Twilight Town's Old Mansion, questioning her own existence and the fate that will soon befall Roxas. She discovers that she is not a Nobody, but an imperfect Replica of Sora created as a fail-safe in case Sora and Roxas turned out to be useless to the Organization's plans. Naminé also reveals that as a memory being, once Xion returns to Sora everyone's memories of her will inevitably be forgotten. Furthermore, Naminé's attempts to restore Sora's memories not only affect Roxas, but Xion as well, stating why they both keep having memory relapses throughout the game. Xion accepts the facts, and decides to go back to Sora. Before she does, though, DiZ barges in with the news that an Organization member has followed her, in which Xion says she will take care of it, despite Naminé's protests, and heads out of the mansion.
It is Axel who has arrived, having finally tracked Xion down. Not only is Axel curious of Xion's motives, he is also given specific orders to capture her again, which would possibly convince Roxas to return to the Organization. Xion refuses, leaving Axel no choice but to accomplish his mission with full force, leading to a heated battle. Having defeated Xion, Axel brings her back to The World That Never Was, but soon faints from fatigue. Xemnas then steps out from the shadows and carries the unconscious Xion away to reprogram her to use the devices he had planted throughout the worlds.
Soon afterwards, Roxas finds Xion at the Twilight Town train station, and after she reveals her altered, Sora-like form to him, she explains that she has been compelled by Xemnas to absorb Roxas and become a "full" Sora, which would in turn prevent the real Sora from ever waking. It is explained in her Secret Reports that this is somewhat of a ruse - she knows that Roxas will disappear if she continues to exist, so she plans to force Roxas to absorb her, saving himself and thwarting Xemnas. She then transforms into a monstrous version of Sora using Xemnas's devices, and attacks.
During the battle, Roxas and Xion are transported to Wonderland, Halloween Town, and Agrabah, before returning to Twilight Town. In each world, Xion absorbs power from the "devices" that were placed there, which contain memories of Sora's battles in each world. After a long and grueling battle, Roxas manages to defeat her, while she regains her original appearance in his view. When done, he doesn't seem to recall who she is, though she assures him that he'll be better off now. Cradling her in his arms, Roxas shares an emotional conversation with her, during which she explains to him that she had no regrets for meeting him or Axel, reveals the true colors of the Organization to him, and pleads with him not to let Xemnas win before dying peacefully in his arms. Saddened, Roxas suddenly remembers her name and holds Xion's hand as her body crystallizes and disintegrates into nothingness, leaving behind a single Thalassa Shell.
Though Naminé states that everyone's memories of Xion will vanish when she does, Roxas, Riku, Xemnas, and Saïx manage to retain some memories of her into the next day. By then, Roxas has returned to the World That Never Was in order to set Kingdom Hearts free, which he hopes will reunite him with Xion. However, he is being stalked by a swarm of Neoshadow Heartless, as well as a determined Riku, who has arrived to capture Roxas to finish Sora's memory restoration. Riku looks down upon the Nobody, before Roxas starts his path up the skyscraper. Through him, Xion is able to throw the Oblivion Keyblade to Riku in order to tell him to stop Roxas before he can reach Xemnas, because she believes Roxas is not strong enough to face him yet. In turn, touching the Oblivion causes Riku to recall flashbacks of the time he spent together with Xion, putting him in shock for a moment. The flashbacks then reoccur when he reaches the ground to face the Neoshadows, but this time turn blurred and grainier as they continue, until only film static, most likely meaning their total withdrawal from Riku's memories.
When Roxas and Riku finish eradicating the Heartless, they turn on each other for a battle. By this time, it is a struggle for Roxas to even remember Xion's name, and all he knows about her is that he wants her back. While Roxas is able to knock Riku down first, Xion then projects her words to Riku, somehow telepathically, to stop Roxas at any cost, and so he does once he removes his blindfold and transforms into Riku-Ansem. Unconscious, Roxas hears Xion talking to him through his mind, telling him not to be sad, as she has become one with him and Sora, and that soon Roxas will also join them. Despite the fact that memories of Xion have been forgotten by everyone, she tells him that she still has her own memories, so she doesn't mind that he has forgotten her, as she won't forget him or Axel. As Riku knocks him out, Roxas's last memories of Xion fade away.
Kingdom Hearts CodedEdit
In the Data Castle Oblivion, the data Naminé reveals to Data Sora and King Mickey that Xion is one of the people that, while gone, is still connected to Sora's heart.
After Aqua speaks with Ansem the Wise about Sora, Xion is sitting atop the Twilight Town clock tower and eating sea-salt ice cream with her friends (Roxas and Axel). Then, Xion and Roxas say Sora's name while watching the sunset together.
Kingdom Hearts 3D: Dream Drop DistanceEdit
Xion appears during the opening sequence, where she points at Roxas with her Kingdom Key. The scene then changes to another scene, where Xion is seen having fun with Roxas and Axel on top of the Twilight Town clocktower. The scene changes back and Xion vanishes into fragments of light.
Xion then appears to Sora in the World That Never Was. Sora takes a grip of Naminé's wrist, but then Naminé turns into Xion. Sora then sheds a tear (most likely because of Roxas inside of him) and wonders who the girl is. Xion then pulls away from Sora and runs away from him.
Xion later appears on Destiny Islands inside Sora's heart. She is sitting on the Paopu Tree and Riku initially mistakes her to be Sora. Xion watches the sunset and asks Riku, "What do you want outta life?" Riku can then choose from three options like Sora did in the original Kingdom Hearts. Xion disappears after Riku gives her an answer.
Story of Joining the TeamEdit
When Sora and company were looking in Castle Oblivion for more answers, their hearts felt like they were remembering someone, and Lea mentioned about a girl with a name that starts with an X. Everyone tried to remember her, but when Lock, Shock, and Barrel came, they suggested if Donald Duck, and King Mickey to use their magic to help remember, and when they did, Shock began to use one of her new powers to help. When they were close, Kairi and Sora added their keyblade magic to increase it, and from their hearts, Xion appeared and hugged everyone that brought her back to existance, and as she explained about why she appeared in their visions, and how she disappeared, everyone was happy to see her again and finally remembered everything and joined Sora's Team.