**Sora’s erasure:**  
When Sora faded from existence, fans assumed that his entire existence fades away.  During that moment on the Paopu Fruit Tree, we see Sora’s vessel and soul fade away, but we are left entirely blank when it comes to Sora’s heart.  You see, in the lore of KH, when a heart usually reaches its last moments, it is removed from the vessel so that it may be absorbed by Kingdom Hearts.  Kingdom Hearts is the origin point of all hearts—according to established lore within the series— so this is what occurs once a soul has perished.  But when we see Sora fade away, his heart never leaves his body and we never do see it.

**The Black Box:**  
Fans believe the Masters’ ‘black box’ contains either his copy of the book of prophecies, an ancient weapon, or the primordial darknesses.  But Tetsuya Nomura deliberately skipped the plot of ‘Pirates of the Caribbean: Dead Man’s Chest’ and opted for an adaptation of the next film in the franchise ‘Pirates of the Caribbean: At Worlds End’ instead.  Tetsuya stated that, they wanted to have a vast open ocean for players to explore so they can captain a ship and travel to diverse islands.  While this was exciting, it feels like Tetsuya did this for other reasons. The plot of the movie that he skipped in particular, is literally about locking a dead man’s heart in a box.  This should be groundbreaking news regarding the “black box” and what its true purpose is.  My theory—The Triangular Paradox Theory—explains that the Masters’ box essentially acts as a container or a “vessel” for Sora’s heart before it is erased along with Sora’s vessel and soul.

**The Rules of Unreality:**  
In the trailer for KH4, we see Sora wake up in Strelitzia’s apartment in Quadratum.  Fans believe Quadratum is ultimately a spiritual afterlife, or purgatory for Keyblade wielders who just happened to fade from existence due to extraordinary circumstances, but this is entirely false.  The secret epilogue of KH3 debunks that theory, Yozora is the sole reason why Sora ends up in Quadratum.  It isn’t the universe planting him there.  Yozora “saved” him.  
The reason why fans speculate this and believe it, is because of Strelitzia’s dialogue.  She states that Quadratum is an “afterworld” and fans have taken what she says deliberately and I feel that is a mistake.  
Sora wakes up in her apartment, he breathes, he has all of his senses, and he functions perfectly fine despite lacking his heart.  In reality (The Realm of Light and Darkness) a heartless-vessel would become a nobody.  Therefore, Unreality MUST work extremely different than that of Reality.  What I theorize—extending off of The Triangular Paradox of course—is that the Realm of Unreality runs on a quantized atmosphere which is identical to real-life biology.  Meaning the literal air Sora breathes within unreality, allows his vessel and soul to operate independent of a heart.  To prove this, in KH3, when Sora speaks with ‘The Nameless Star’, Sora talks to her about belief and the process of believing in something.  ‘The Nameless Star’ is noticeably puzzled at what belief is, it’s as if she’s never heard of it before.  Could this be because she doesn’t have a heart in the same sense Sora does during that moment in the final world?

**Sora’s amnesia:**  
As Sora is being guided around the city of Quadratum by Strelitzia, Donald and Goofy magically appears in front of Sora without warning.  It is safe to assume that they navigated the Underworld in search for Sora first, and then was given direct clues as to where he is by Hades.  Hades being the Lord of the Dead, it would make narrative sense why Donald and Goofy would travel here.  Hades uses his powers to tap into the Astral Plane, and this is how Donald and Goofy appears in front of Sora.  Sora’s reaction left fans confused, they couldn’t understand how the boy that spent most of his life around a duck, and a tall dog, would faint after seeing them after a few days.  The truth lies in Quadratums laws and rules of existence.  If Sora’s heart isn’t with him, and his vessel and soul are operating without his heart, then that literally means that Sora has no way of remembering Donald and Goofy.  The heart retains memories, and with my theory, I established that Yozora’s actions could have caused Sora’s memories to be scattered across the worlds in unreality, but because Sora’s heart is locked away tightly inside the box, he cannot remember his deepest most cherished memories.

[KH THEORY] The Triangular Paradox Manifesto (TL;DR)