Was taking with a friend about KH character development and a thought came to mind: what if Riku is a nobody? A nobody who developed into a separate and sentient person. This idea is suggested with Roxas as Sora believes that he is his own person and deserves his own life and even exists within Sora as a separate entity. We also known that wielding keyblades does not require one to be an full person, Roxas, Xion, Replica Riku show this, I’m sure other examples exist.
We do know that the light from Riku’s heart was the main thing that drew Terra to Destiny Islands and subsequently caused him to make Riku an heir to the keyblade. We also know that between that and the start of KH 1 a tremendous darkness to hold of Riku. My thought is that it was during this period that Riku came to be a Nobody. Since a nobody can still wield a keyblade nothing would be affected in that regard. The main question would come with his heart.
The easiest way to think of a Nobody is an incomplete person. Remember that a heartless is essentially the physical manifestation of the darkness in a person’s heart, so without heart and darkness the nobody is in a way hollow. They cannot fully experience anything, pain, pleasure, emotion, etc. And I do mean that in the metaphysical way. They can experience the world around them but not truly understand it. Sort of like seeing a crying child and not being able to sympathize or empathize with them. This is how I see the Nobody’s. Further we can accept via Roxas that a Nobody could possibly transcend into a full person with light and dark parts. Keeping in mind that light and dark are not good and evil but rather masculine/feminine, introvert/extrovert, and so on.
This means a Nobody could come to experience the world enough to become their own person. I believe that happened with RIku and is why he goes from a child of light at around 8 to a servant of darkness at 15, because he was not truly the same person. Just as Roxas and Sora are not the same person so too could whoever Riku was beforehand and he not be the same person. In this sense it would explain a certain amount of Riku’s unique ability to control darkness and to never fully succumb to it. Because perhaps once someone has succumbed to darkness and become heartless and nobody, then perhaps the process cannot be repeated until such time that the Nobody is a full person. And Riku for a while seemed to be very similar to the members of ORG XIII, beyond the trench coats.
Just something to ponder. A good question is if the original person that is now Riku comes back like Lea did, since Riku is his own being, would they technically be twins?