Hai hai! i used to be on this site before as XIVth Member, but I forgot my password so I'm here again as XIV Xion. If anyone can remember me, I'm a GREAT theorist and have done tons of research on everything Kingdom Hearts. If you need a good arguement or information, I'm the person to come too!
Building on this Theory and many others, it seems that Xion is indeed a combination of Sora and Kairi, and the "Oni" Name is indeed the original, if not then a mere connection(Good job Enix, another connection.) to the name's meaning. Namine' is Kairi's Nobody. Roxas is Sora's Nobody. The Heart Unlocker created Roxas AND Xion. Releasing the Heart of Kairi and Sora, Her looks and his ablilties(and eyes if noone noticed) became the imperfect abomination that is Xion(Oni meaning the irregular creation of it, and a nice spin on it to keep Organization tradition, making it Xion. This game is originally Japenese with English elements, consider it.) Xion is the irregular imperfect Nobody of Sora and Kairi. She can weild the keyblade, which is why she is entered into the Organization. They do not know who she is. Her memories are of Sora and Kairi's which is why she seems out Riku to a answer as to who she really is and why she has those memories. Xion was never meant to have those memeories. Nobodies should never exist, but Xion is the ultimate abomination. The Organization finds out who she really is and gets rid of her, despite her being able to weild the keyblade. She held memories that could drive away Roxas and herself in the process, that's why they decided to kill her. That gets Roxas thinking about who he really is and leaves the organization. See Kingdom Hearts II for continuation of this story. OH HELMS YEAH!!!
For now her character does not make ANY sense, nor does the connection with Axel on both Roxas and Xion's account. Xion looks like Kairi, sounds like Kairi, can weild a keyblade like Kairi. However, the names of the organization members(not every Nobody with human form) are variations of original names with a X put into them. Axel has been proven to not be Riku's nobody(as far as my knowledge goes, I am recently picking back up Kingdom Hearts and all my previous knowledge has gone to mush), and Namine' was supposively Kairi's nobody? She is trying to get away form the organization and Axel keeps bringing her back. She continously meets up with Riku, but as for romantics, I think not.
