My Theory On KH:

Many people have different theories on the Kingdom hearts series. Here is mine:

BIRTH BY SLEEP

Ven's heart was split in two. The darkness was extracted and it created Vanitas. After Ven had merged his heart with Sora's, Vanitas had started to look like Sora in KH2. It is weird because it gives the fact that maybe hearts are the only way to the future, as Sora was only a little boy, and had not looked like his 17 year old self. This is a question yet unanswered.

KINGDOM HEARTS

Near the end of the game, in Hollow Bastion, when Sora stabs himself, it extracts Ven's heart from Sora's, and creates Roxas. This explains his resemblance to Ven, as the two are easily mixed up, but also explains the reason Sora survived, because he still had a heart.

CHAIN OF MEMORIES

Sora travels through Castle Oblivion, losing his memories, he meets Axel, but I don't understand that he never remembered him in KH2.

358/2 DAYS

This game starts near KH1, when Sora stabs himself. But, when Kairi hugs Sora as a heartless, the second that he becomes himself, Xion is created. If you haven't noticed, Xion looks like Kairi (from KH1)  only with shorter hair. Once Xion dies, she resides in Roxas, and then Roxas eventually resides into Sora in...

KINGDOM HEARTS 2

Roxas never resides into Sora in the beginning, as he had the chance to fight Sora in his old fashioned Organization XIII Cloak. Near the end, he finally resides in Sora. So the theory that Roxas and Xion saw Axel die is incorrect. Axel was defeated and Xion was inside Roxas and Roxas was not in Sora at the time. Another thing to add on to that, Sora never had a tear in his eye when he saw Axel die, but he did when Hayner Pence and Olette said goodbye, for the reason that Roxas was part of him at the time. He then extracted himself from Sora and fought him.

Re:CODED

In the datascape, Data-Sora saved the day, but at the ending cutscenes, they started talking about the real Sora. This game takes place after KH2, because the ending cutscenes is Mickey sending Sora a letter, telling him and Riku to travel to Merlin's tower, for their mark of mastery exam. The letter also hints Ventus, Aqua, and Terra, maybe suggesting they are saved from their terrible fates (especially Terra) in KH3

DREAM DROP DISTANCE

Sora fails the Mark of Mastery exam, but learns more about Ventus Aqua and Terra. Riku is now a keyblade master, so maybe he would show up in KH3.

  Until then, this is Joey, cranking out posts left and write.