Xion

Xion is the fourteenth member of Organization XIII, and is to appear in the upcoming game Kingdom Hearts 358/2 Days. At the Square-Enix press conference DK∑3713, she was revealed in a trailer to have strange connections to both Naminé and Kairi. A recent Famitsu article states that she has a "tragic yet, brave fate." Xion has been shown in pain being held in Riku's arms, questioning her existence, indicating that her fate may indeed be tragic. Axel is quoted saying that no matter how often Xion tries to escape, he will always bring her back. This suggests that Xion could possibly be trying to leave the Organization as Roxas did.

Xion's face seems to resemble Kairi's/Naminé's and her hair style is similar to Kairi's Kingdom Hearts hair style except black. Their resemblance has been underscored by the trailers. She also seems to have a similar personality, kind and caring like Kairi and pretty depressed like Namine. Though, she seems a bit easier to anger, namely when Riku called her Keyblade a fake.

Xion appears to be good friends with Axel and Roxas, and they are often seen hanging out together in Destiny Islands and Twilight Town. She seems to be rather kind, aiding Axel and Roxas in one mission and talking respectfully to Riku at Destiny Islands. She mentions to Riku that she has an important friend, and asks about "that girl who was with Sora," referring to Kairi. Riku tells Xion she "must return to her true self," but she seems reluctant to do so, likely due to her friends. Roxas and Axel both confront Xion in Twilight Town, where she raises her Keyblade to fend off Roxas when he approaches her. In a newly-released trailer, after this point, Axel attacks her and they engage in a heated battle, while Roxas shouts for them to stop. When Axel meets her in front of the Twilight Town mansion, she tells Axel that she is returning to where she belongs, while Axel thinks there has to be another way. Shortly after she summons her Keyblade and orders him not to go easy on her, and Axel summons his chakrams. Her fate is currently unknown.

In the newest trailer, she and Roxas are on the station tower in Twilight Town. She stands up and takes off her hood, though none of her head except her mouth is shown. Roxas looked surprised. Xion quoted, "My power will soon be fulfilled... like a vessel overflowing with water... Now, my memory is full of memories of Roxas... Roxas, how do I appear to you now?"

Special Abilities
At the Square-Enix press conference DK∑3713, she was revealed in a trailer to wield the Kingdom Key. Although she wields a Keyblade in release trailers, it is unknown if hers is a real Keyblade, as Riku claims Xion's is a fake. Naminé also makes a reference to Xion while talking to DiZ when discussing Sora's memory restoration. Naminé mentions that if those memories begin to "leak" while being connected, and if those memories are connected to other memories, then those "leaked" memories cannot be restored. Naminé then questions if Xion could endure such a thing, confusing DiZ.

Theories
One theory is that unlike Naminé, who is a Nobody of Kairi born from Sora's body, Xion could be a Nobody born solely of Kairi, or a Nobody of Sora born from Kairi's body. The opposing color schemes the two Nobodies have could represent their opposing births. However, Xion's name does not fit the naming scheme of the other Organization members, as it should be an anagram of "Kairi" and "X" if she was Kairi's Nobody. However, her name could in fact follow the naming scheme which Xehanort's does - If the "X" is removed, his name is an anagram of "No Heart" and "Another". Xion's name easily fits this pattern - for her, the anagram would be "No I", possibly implying that unlike the other Organization members, she doesn't have a somebody. This would also play into the reason why the Organization remains "Organization XIII", even with her in its ranks. However, the theory does not explain how Xion knows of Sora and Kairi, or Riku's statement that she "must return to her true self", perhaps referring to Kairi. Possibly, Sora's "leaked" memories fused with Xion after the Castle Oblivion incident, explaining Naminé's question as to whether or not Xion could endure it, maybe meaning if Xion could endure giving the memory back to Sora, which could lead to her tragic fate. Either way, she could be encasing some of Sora's memories, causing her to have a similar existence of a Heartless with the characteristics of a Nobody. It is for certain she has some ties between Sora, Kairi, Riku, and Naminé. Also Xion could be the result of his memories of Kairi or the embodiment of Sora's leaked memories, meaning that Sora may have lost memories having to do with Kairi, or the merely just all of Sora's lost memories taking the shape of someone who meant much to Sora, which could double as explanations of returning to the person from where she came, and her Keyblade. Her keyblade could have been forged out of the possible lost memories of the Keyblade, which explains why Sora forgot his abilities (ex. Ragnarok, Sonic Blade) and magic, from Kingdom Hearts, when he woke up in Kingdom Hearts II.

Another, very likely part of Xion's demise is that Naminé may have erased everyone's memories of her. This is supported by the facts that, even though she appeared in a game set before Kingdom Hearts II, no one ever makes any mention of her in ''Kingdom Hearts II'.

Althought it is still debatable as too if her relationship with Axel is on par with that of Roxas, there seems to be a deep connection between the three. However, there has been much speculation, especially with Axel's dialogue as to if Axel felt some jealousy over the relationship Roxas held with Xion. This could be to do with the connection Roxas and Xion have through Sora and Kairi.

Xion has been shown saying to Riku, "Do you hate me for taking away your friends?" on Destiny Islands. Riku replies, "No. But I'm sad.", so one has to wonder if she has something to do with Riku's memories, along with Sora's.

Trivia

 * Xion is said to have ties between both Kairi and Naminé, suggesting that there is a relation between the three of them.
 * Like Roxas, Axel, and Naminé, Xion is suspected of having true emotions.
 * In a cutscene for 358/2 Days, Roxas, Axel and Xion are seen at Destiny Islands sitting on the paopu tree. Interestingly, their positions mirror those of Sora, Riku and Kairi in the original Kingdom Hearts game. Roxas was sitting where Sora was sitting (interesting, as Roxas is Sora's Nobody), Xion was sitting where Kairi was sitting (also interesting, as Xion is said to have "connections" with Kairi) and Axel was leaning against the tree just as Riku was (perhaps implying some kind of connection also; one possible reason is because Axel is best friends with Roxas, as Riku is with Sora, or perhaps because Axel is seen as the powerful member of this trio, and mirroring Riku, is jealous of Roxas, despite his being a nobody).
 * Apparently, Xion possesses no memory of her original self. It is possible she had an unusual birth, like Roxas and Naminé as they both had none of Sora's and Kairi's memories because of their unusual births. However, it is being suggested that throughout the game, Xion appears to regain memories of Sora and Kairi.
 * A cutscene has shown that the other 13 members of the Organization, including those that appeared in Chain of Memories, were present when Xion joined, so it seems that she joined sometime before (or during) when Sora arrived at Castle Oblivion.
 * In a cut-scene of 358/2 Days, Ansem the Wise (as DiZ) and Naminé are shown standing in front of Sora's pod in the mansion; Naminé mentions that, "if more memory leaks out", she will not be able to take it in. Diz responds with a puzzled tone, "She?", possibly speaking of Xion.

Xion