Theories About Kingdom Hearts’ Master of Masters
He’s the Contents of the Black Box, More Specifically His Heart
This is one of the theories that say the Master is an entirely original character, with a master (haha) plan. Hearts are, obviously, a huge part of the series, and for this one the Master put himself into the mysterious Black Box, or his heart.
This would allow him to see out his remaining days with the Foretellers as a Nobody, influencing them to start the Keyblade war, but keep his heart safe from the end of the world. Then by giving Luxu the task of protecting the box and seeing out the future, the Master awaits the moment of the box being opened.
As YouTuber Glitchy explains, there are multiple points where Xehanort references the Book of Prophecies, including in Dream Drop Distance where he explains to Mickey and the others that he doesn’t possess the foresight to see the future, but he knows about the fated time he’ll meet his twelve other selves.
Now the only ones that were given copies of the Book of Prophecies were the Foretellers, not even Luxu was given one. Therefore it’s possible the Master contacted Xehanort either by time traveling or through his heart in the box, telling him what to do in the future.
While Luxu’s task was to keep the box safe, he served a dual purpose to pass on the Master’s Keyblade and groom the perfect vessel. We know the Seekers of Darkness are looking for the Black Box in Kingdom Hearts 3, and perhaps the saga could end with Xehanort opening the box and the Master’s heart finally having the perfect vessel to inhabit.
Nomura has stated in the past that the Master won’t appear in Kingdom Hearts 3, however, that could simply mean his physical incarnation as we know it. Nomura could also not have meant the Epilogue and Secret Ending, which will be arriving after the release of Kingdom Hearts 3 as an add-on, and technically aren’t part of the base game.
