Unfortunately this is a part of another Unbirth theory. But since the forums are a little dry as of late, I thought, "What the hell, why not."
Anyway, I was thinking about the theory that, somehow, Unbirth are memories (especially since BbS will have a focus on Xehanort's memories and Days will focus on memories as well). It's logical because memories have no means by which they could reproduce (Heartless have darkness, Nobodies have Nothing), and since, as Namine said, memories are not naturally lost (only forgotten). So if, say, Master Xehanort was creating them, then once MX was gone, they would stop being created. And that would explain their disappearance, seeing as how they'd have no means by which they could keep producing.
Then I thought about how the Unbirth could potentially be the "starting point" of the Heartless and Nobodies. Nomura makes it sound as though the Unbirths are precursors for the other two enemies. So I started wondering about how Heartless and Nobodies are created:
1. The Heart is separated from the Body and Soul
2. Darkness engulfs the Heart and creates a Heartless
3. The leftover Body and Soul are reborn as a Nobody
But then I realized something. There's a fourth, though minor, step in the process:
4. The Memories leave the Heart and go to the Nobody (This is confirmed by various Nomura interviews as well as the Secret Ansem Reports. I don't feel like looking them up right now, but if you want proof, just ask. Also, don't bring up Roxas as a contradiction. The memories WERE going to go to him, until Sora was revived from his Heartless state.)
So while I pondered how this fourth step could possibly act as a "starting point," another question popped into my mind:
Where do the memories go when no Nobody is created?
That question is what I'd like some feedback on. While I don't think this has anything to do with Unbirths, it's still puzzling. Do the memories go somewhere? Or do they stay in the Heartless? (Problem with that second question is... If the memories stay in the Heartless, why, then, would they go to the Nobody in the first place when a Nobody is created if they could just stay inside the Heartless?)
That's the bulk of what I wanted to say, but now I want to introduce something. I thought of this theory and while I doubt it, I'd find it amusing to share.
So on the topic of the potential for when no Nobody is created, I started thinking about the past when Nobodies and Heartless weren't around. And I thought, "So what happened to the memories back then when someone was lost to the darkness?" We know that people did get lost to darkness, as AtW himself witnessed it.
I also thought about how the term Birth by Sleep, which is more likely than not connected to the Unbirths, could be a reference to the Awakening of a Keyblade wielder.
Since Birth by Sleep could be connected to Unbirths, that would mean Birth by Sleep, if the Unbirth memory theory is right, is also connected to memories. This statement provides evidence:
"Hidden Days are Born from Sleep."
(An old trailer for the three new KH games ended in saying "Hidden" for coded, "Days are" for 358/2 Days and "Born from Sleep" for BbS to form one sentence).
Hidden Days. Could that mean lost memories?
Anyway, using all of these theories and info, I came up with this:
When someone chosen to wield the keyblade fails their Dive into the Heart (when their darkness consumes them in that final fight, like Sora and Roxas with Darkside and Twilight Thorn, only they aren't strong enough to overcome it) their being perishes. Because the heart is consumed by darkness, the same process that happens with Heartless and Nobodies happens to that failed Keyblade wielder, the memories are released. Somehow, MX turns these memories into Unbirths, born of the person's sleep (maybe they manifest in Castle Oblivion or something).
Amusing and mildly interesting, no? (No, I don't believe it, but I had to let it out)
Anyway, I was thinking about the theory that, somehow, Unbirth are memories (especially since BbS will have a focus on Xehanort's memories and Days will focus on memories as well). It's logical because memories have no means by which they could reproduce (Heartless have darkness, Nobodies have Nothing), and since, as Namine said, memories are not naturally lost (only forgotten). So if, say, Master Xehanort was creating them, then once MX was gone, they would stop being created. And that would explain their disappearance, seeing as how they'd have no means by which they could keep producing.
Then I thought about how the Unbirth could potentially be the "starting point" of the Heartless and Nobodies. Nomura makes it sound as though the Unbirths are precursors for the other two enemies. So I started wondering about how Heartless and Nobodies are created:
1. The Heart is separated from the Body and Soul
2. Darkness engulfs the Heart and creates a Heartless
3. The leftover Body and Soul are reborn as a Nobody
But then I realized something. There's a fourth, though minor, step in the process:
4. The Memories leave the Heart and go to the Nobody (This is confirmed by various Nomura interviews as well as the Secret Ansem Reports. I don't feel like looking them up right now, but if you want proof, just ask. Also, don't bring up Roxas as a contradiction. The memories WERE going to go to him, until Sora was revived from his Heartless state.)
So while I pondered how this fourth step could possibly act as a "starting point," another question popped into my mind:
Where do the memories go when no Nobody is created?
That question is what I'd like some feedback on. While I don't think this has anything to do with Unbirths, it's still puzzling. Do the memories go somewhere? Or do they stay in the Heartless? (Problem with that second question is... If the memories stay in the Heartless, why, then, would they go to the Nobody in the first place when a Nobody is created if they could just stay inside the Heartless?)
That's the bulk of what I wanted to say, but now I want to introduce something. I thought of this theory and while I doubt it, I'd find it amusing to share.
So on the topic of the potential for when no Nobody is created, I started thinking about the past when Nobodies and Heartless weren't around. And I thought, "So what happened to the memories back then when someone was lost to the darkness?" We know that people did get lost to darkness, as AtW himself witnessed it.
I also thought about how the term Birth by Sleep, which is more likely than not connected to the Unbirths, could be a reference to the Awakening of a Keyblade wielder.
Since Birth by Sleep could be connected to Unbirths, that would mean Birth by Sleep, if the Unbirth memory theory is right, is also connected to memories. This statement provides evidence:
"Hidden Days are Born from Sleep."
(An old trailer for the three new KH games ended in saying "Hidden" for coded, "Days are" for 358/2 Days and "Born from Sleep" for BbS to form one sentence).
Hidden Days. Could that mean lost memories?
Anyway, using all of these theories and info, I came up with this:
When someone chosen to wield the keyblade fails their Dive into the Heart (when their darkness consumes them in that final fight, like Sora and Roxas with Darkside and Twilight Thorn, only they aren't strong enough to overcome it) their being perishes. Because the heart is consumed by darkness, the same process that happens with Heartless and Nobodies happens to that failed Keyblade wielder, the memories are released. Somehow, MX turns these memories into Unbirths, born of the person's sleep (maybe they manifest in Castle Oblivion or something).
Amusing and mildly interesting, no? (No, I don't believe it, but I had to let it out)