Probably similar theories exist, but I want to share my version.
During the Void century things happened we don't know of. An ancient kingdom dissapeared. Joyboy couldn't keep his promises. A giant elephant did something he wasn't allowed to do. And the neverending energy supply, the eternal flame, ended. The D clan became the natural enemies of the Celestial Dragons.
So what if 800 years ago, many kingdoms lived in peace. One kingdom thrived in technology. It used solar power to make everything work. It was the future. Other kingdoms were a bit scared but for a while it went good. Joyboy from the ancient kingdom was the one keeping peace. And with his Nika fruit he could control the Sun. But the other kingdoms became more scared, because technology means power and the thought of them being taken over drove them too crazy thoughts. The destruction of the ancient kingdom. They decided to start the World Gouvernment and destroyed the ancient kingdom. They used the technology and ancient weapons against them and when all was finished, they used the Yami Yami no Mi to take away the power of the sun, making it a moon. The eternal flame ended. And Joyboy couldn't keep his promise of bringing together all kingdoms by technology. The D clan are the descendants of the Ancient Kingdom. Enemies of the ancient royals by history. Behind the schemes of this all Imu/Lilly rised to be the secret ruler. Now 800 years later, Blackbeard is out for revenge on the Celestial Dragons, Imu feels things are taking a bad turn now that the Yami and Nika fruit are back and Luffy just wants joy. Luffy is the peacebringer. The one that will get between Blackbeard and Imu. The one that will show that history doesn't mean we are responsible for what past generations did. And that a good future needs a everyone happy, working together and accepting technology. Luffy will liberate the world of its history. When everything is fine, Luffy will go the moon. And with has last peace a lifespan left after his adventures, with a big smile, the moon will start burning and the sun will rise once again. The eternal flame is back!
During the Void century things happened we don't know of. An ancient kingdom dissapeared. Joyboy couldn't keep his promises. A giant elephant did something he wasn't allowed to do. And the neverending energy supply, the eternal flame, ended. The D clan became the natural enemies of the Celestial Dragons.
So what if 800 years ago, many kingdoms lived in peace. One kingdom thrived in technology. It used solar power to make everything work. It was the future. Other kingdoms were a bit scared but for a while it went good. Joyboy from the ancient kingdom was the one keeping peace. And with his Nika fruit he could control the Sun. But the other kingdoms became more scared, because technology means power and the thought of them being taken over drove them too crazy thoughts. The destruction of the ancient kingdom. They decided to start the World Gouvernment and destroyed the ancient kingdom. They used the technology and ancient weapons against them and when all was finished, they used the Yami Yami no Mi to take away the power of the sun, making it a moon. The eternal flame ended. And Joyboy couldn't keep his promise of bringing together all kingdoms by technology. The D clan are the descendants of the Ancient Kingdom. Enemies of the ancient royals by history. Behind the schemes of this all Imu/Lilly rised to be the secret ruler. Now 800 years later, Blackbeard is out for revenge on the Celestial Dragons, Imu feels things are taking a bad turn now that the Yami and Nika fruit are back and Luffy just wants joy. Luffy is the peacebringer. The one that will get between Blackbeard and Imu. The one that will show that history doesn't mean we are responsible for what past generations did. And that a good future needs a everyone happy, working together and accepting technology. Luffy will liberate the world of its history. When everything is fine, Luffy will go the moon. And with has last peace a lifespan left after his adventures, with a big smile, the moon will start burning and the sun will rise once again. The eternal flame is back!
