Xion

Xion is the fourteenth member of Organization XIII, to appear in the upcoming game Kingdom Hearts 358/2 Days. AtSUCK MY DICK.RICKY RULES some kind of Keyblade and to have connections to both Naminé and Kairi.

Little is known about her role in the game. She has now shown up twice: once in Twilight Town, where she aided Roxas and Axel, and again in Beast's Castle, where she and Riku had a verbal showdown.

Although she wields a keyblade in the most recent video, it is unknown if this is a real keyblade, or if, as Riku suggests, it is a fake, though some speculate that he was most likely just not willing to accept the fact that someone else could wield the Keyblade other than himself or Sora. Her Keyblade from the trailer has been revealed to be the Kingdom Key, Sora's original Keyblade, from many sources. Naminé also makes a reference to her while talking to DiZ, talking about connecting memories.

There is still no confirmation on a power, though she's revealed to look and sound like Kairi and have dark blue hair, similar to Aqua's.

Speculation
Currently, due to the lack of official information, there is much speculation about how Xion fits into the Organization XIII. While no information or rumors exist to why, several have been formed on a connection with Sora. One said rumor states that Sora's memories are to be reconstructed inside of Xion, explaining the Keyblade. Also, Naminé was quoted wondering if Xion could handle his memories. Based on one theory that Xion's origin derives in some way from the union of Sora's and Kairi's hearts in Sora's one body, it has even been speculated that the name "Xion" is an anagram of the letters "I" and "O" from Kairi's and Sora's names, respectively, as well as an "N," from Naminé's name or perhaps from the word "nothing," and an "X." Axel was quoted saying that Xion often tries to escape, and he always brings her back. This suggests that Xion is not in the Organization on her own will, but is forcibly kept a member. A theory of the reason behind the Organization's name being kept as Organization XIII is seemingly because Xion is not a Nobody, but the Organization uses her because she is able to wield the Keyblade.