This character was intriguing from the start, and has proved that Nomura still rocks at absolutely confusing his fans. I have a theory on Yozora that i wanna get out there and wanna see some opinions.
This is a fairly common theory that I believe might have some real footing. I believe Yozora is an inversion of Sora. Like Yozora's name legit means night sky and Sora's means sky. Some evidence for this is when they first interact before they fight. Yozora mentions in order to get to the Final World (or what appears to be a digital version of it) he had to go through trials. In order to unlock the Yozora boss battle, you have to finish the DLC and the limit cut episode and fight data versions of member of the True Organization XIII, which seems like a type of trial. The second is when Yozora and Sora have share the same dialogue at the end of the fight, which are the first lines players here Sora say at the beginning of Kingdom Hearts 1. And idk having alternate dimensions with alternate versions of characters seems like something Nomura would do. We already have enemies that represent the heart and body of individuals, i feel like one of the natural steps after that are mirror world in a sense. I'd also like to hear some thoughts about how this ties in with Versus-XII and Final Fantasy XIII in general since i know nothing when it comes to Final Fantasy.