There weren't any Heartless or Nobodies in Birth by Sleep. That's the only flaw I see in your theory. Xehanort and his colleagues kept people they experimented on in the basement of the Hollow Bastion, therefore creating Heartless. As for the Room of Sleep, Xigbar also said that "...with the Room of Sleep comes the Room of Awakening." What this means I can only imagine...
yeah okay there weren't any heartless and nobody's. but maybe he was the first one who let his heart taken by darkness, or he have given his heart to darkness for more power. then he can become the first heartless and nobody. and he and sora were the only one who turned back to human from a heartless. and the heartless(ansem seeker of the darkness) was stil there so in the past he must have turned back from a heartless what made that he have 2 nobody's.
In TWTNW:
Vexen: Zexion! Zexion!
Zexion: What's all the fuss about?
Vexen: Where's Xemnas?
Zexion: At the usual place.
Vexen: The "Room of Sleep"?
Zexion: If it's urgent, why don't you go and see?
Vexen: Stop joking around! I will await his return. I must.
This is what happens when we need him and he sleeps. Now, of all times...
Xigbar: I'm not so good in that place either. How about you, mister Zexion?
Zexion: What are you doing, eavesdropping like this? The mission assigned to you and Xaldin was to look for new members. You shouldn't be able to afford wasting time around here.
Xigbar: I'm doing enough work, already! Found another one just yesterday. I think his new name is "Mar-" something or other. With this the Organization now has 11 members. That's quite a number. And so just for today I asked Lexaeus to cover for me so I could take a break... in anticipation of tomorrow's work, that is.
Zexion: Then please rest fully. I have work to do for today so I'll be going...
Xigbar: So harsh of you. I just want us to have a little fun talk about, say, Xemnas' secret. How many years ago was it? People with the blade of keys started to appear and fought great battles. When they were gone, a man who had lost his memories appeared. Xemnas... no... Xehanort was taken in by Ansem around that time, was he not?
Zexion: What of it?
Xigbar: The "Room of Sleep"... the underground laboratory where we were studying the darkness within people's hearts, the place which Ansem ordered us to seal-away... The first thing Xemnas did when he got rid of our wise yet bothersome leader was to release the seal and make that room in the depths of the laboratory. After that he frequently went down there and I could hear him talking with someone. Isn't that odd? Xemnas is supposed to be in there alone.
Zexion: It seems you really enjoy eavesdropping.
Xigbar: I couldn't hear what they were actually saying. And so I feel preoccupied. You're interested too, right?
Zexion: I simply want to concentrate on my assignment. You too should concentrate on your real mission and collect more members. We must hurry with the preperations for our new quarters... 11 Organization members is not enough.
Xigbar: Our new quarters... oh, Castle Oblivion, right? What does Xemnas hope to achieve by using that?
Zexion: We've been told that-
Xigbar: There's a reason, one that hasn't been told to anyone. With the "Room of Sleep" comes the "Room of Awakening", the other place. That is what he is seeking; that room, which was not made by Xemnas. Perhaps that is where the other... "friend" is.
the new scene from final mix what proof a little of my theory.
they fought great battles, maybe MX was so scared of losing from the 3 knights he fully let the darkness in his heart what makes a heartless and a nobody.
Simply astonishing! Today I had a guest from another world. He is a king and, his vessel is built of the material that composed the meteors. He called the pieces "gummi blocks". It seems that my opening that door has opened a path to interworld travel.
We talked for countless hours but one story in particular caught my interest, that of a key called the "keyblade". The keyblade is said to hold phenomenal power.
One legend says its wielder saved the world, while another says he wrought chaos and ruin upon it. I must know what this keyblade is. A key opens doors. It must be connected to the door that I have opened.
why he so interested in this story from the king is maybe because he as human was a keyblade bearer, MX was for a short time a heartless so only the strongest memories get to the nobody, that must be hatred anger and the keyblade. and the story from the king actived his memories again and so he can open the basement of the castle from ATW.
better theory with the others from me combined?