My theory is based on the Ienzo statement that he and Zexion are not the same. I began to wonder what if it really was said in the most direct sense. I see it this way: When nobody comes into the world, he builds his personality by remembering when he was a man, but it is what he builds, thereby re-growing a new heart for himself. Due to the factors that the owner of the heart nobоdy also makes a new heart different from what the original person had, because the new heart is filled with new memories and emotions. When the heartless and nobody are destroyed, then the original heart and the heart of the nobody literally grow together. Watching Lea / Axel personalities, there are differences: Axel, this is a calm and calculating guy, and Lea is a childish and emotionally vulnerable child. What is not surprising because when he became nobody, he was a child, and his entire adult life was nobody Axel, literally an emotionless killer. Therefore, when he is a man again and looks like an adult in his soul, he is still that 15-16 year old Lea, and behave accordingly age, he simply does not know how to because all his adult personality is nobody. Perhaps this also explains why Lea at KH3 is somewhat weak since most of its forces belonged to Axel and only time will help me. Lea seems to fully regain his strength, probably the heart of Lea and the heart of Axel must be fully assimilated for this process to go. Personally, I think Axel is really dead as if it were sad for me, but his heart and memory went to Lea, which, however, does not make him fully the same Axel. Because of the memories of Axel, Lea has an attachment to Roxas and Xion, maybe that's why he wears a coat, asks to call himself "Axel", so that they see him as his nobody, Lea portrays though not fully he. In confirmation of the theory, Nomura said that Lauriam is Lauriam, thus hinting that Marluxia comes from Lauriam, but is not. What do you think about this theory? Can this be at least partly true?