Theories on the nature of the Nobodies. (Contains Spoilers)

Warning, you read this thread, then you understand that there are spoilers here, so do no come whinying to me about posting spoilers without spoiler tags. It is mentioned in the title.

So this thread is to hear theories on Nobodies.

Here is mine.

All being have a heart that inhabit the body. When one's heart is seperated from their body we know that their physical self becomes a heartless. Shown by evidence of Sora. But where does the heart go? We know that as Sora's heart leaves his body Roxas was born. So it would be apparent to me that the heart manifests as a Nobody. This word would has double meaning, aptly describing the bodiless incarnations of the heart. As heartless lack hearts, Nobodies lack bodies. The only reason Roxas continued to exist after Sora's heart returned was because...if I remember correctly there was something special about Roxas, something done to him so he would continue to exist. If my theory is true, then for every Heartless there would be a matching Nobody too.

All this is pretty much what what the game implies.

But, about the part of Roxas having something done to him so he could continue to exist.. Isn't Namine Kairi's nobody? That either mean Namine had the same thing done or that someone's heart returning to them has no effect on the nobodies. Which is possible, as their is no indication as to whether or not a nobody's existence is dependant on the heart of their original.

wow that is cool about Namine and Kairi. But now that I think of that, Namine was wearing white, but that could just be coincedence...Did anybody notice that at the end of COM Marluxia was riding a Nobody in the final battle??

EDIT: http://en.wikipedia.org/wiki/Marluxia#11._Marluxia