Recently we came to know that Kaido has knowledge of Joy Boy. Obviously this is a huge development going forward, but it definitely brings to question, how? Where did Kaido attain knowledge of Joy Boy?
Well I think I can provide an answer that will also help close the book on some other mysteries in the One Piece Universe and it involves the All Blue & the Rocks Pirates and their enigmatic captain: Rocks D. Xebec.
To briefly sum up the All Blue, it’s a rumored legendary sea where all Western, Eastern, Northern & Southern seas flow into one. It is the dream of Sanji to find this legendary body of water, but he’s not the focus of this theory. Now imagine, the concept of water retaining memories. The movie Frozen II takes this concept as its recurring theme. If there was a location in the world where all water flowed and met, it would in theory, hold the history of the world. All it’s history.
This bring us to the second point, Rocks D. Xebec. My theory is that the All Blue has already been discovered before, by the Rocks Pirates and their captain holds a very particular Devil Fruit ability, the Ekō Ekō no Mi [Echo Echo Fruit] It’s based on the concept of psychometry, the ability to discover facts or the history of an item or person through touch.
And as we all know, the World Government has quite the history with silencing people or groups researching or attaining knowledge of the Void Century. Nico Robin & the Scholars of Ohara being the prime example, and possibly even Doflamingo being given his Warlord status in return for his silence.
Do you see what we’re getting at here? Through the use of his Devil Fruit & the All Blue, Rocks attained knowledge of the Void Century, the Will of D., etc… Which leads up to the events at God Valley. Prior to the defining battle, we know that the Rocks Pirates were on their way to attack the World Nobles, and was most likely a full scale assault on Mary Geoise. They were intercepted on the way by Garp & Roger. Why the Roger Pirates were involved is mostly a mystery, but it can be assumed that a notorious pirate crew with knowledge of the most forbidden subject would warrant the World Government & The Marines to seek an extreme solution.
In the aftermath of the battle, obviously the Rocks Pirates disbanded and for some reason Roger procured a sketch of the Road Poneglyph in Totto Land. My assumption being is that Xebec shared knowledge of the Void Century, Laugh Tale and Joy Boy to Roger & Kaido (I’m not sure about the rest of the crew since Whitebeard was a part of the Rocks Pirates but had no knowledge of Laugh Tale & the Will of D. till his last meeting with Roger). This would explain why the battle at God Valley and most knowledge of the Rock Pirates was scrubbed as it did pertain to knowledge of the Void Century.
The Battle of Marineford & the Current Wano Arc I think confirm a majority of my theory as Kaido, Whitebeard, & Oden make direct references to “Joy Boy’s Reincarnation” or “The Man That Roger Is Waiting For”.
*Theory by Stewbuscus