Another bit of evidence that can be regarded as minor when comparing it to the previous bit, is the fact that the Five Elders seem to have exact knowledge of what happened in the Void Century and they seem to care so much about it, that it almost seems as if It has to do with them personally. We know that the World Government wants to hide everything they can about the Void Century, but it does seem to effect the Gorosei to such an extreme that it becomes a bit suspicious.
There are several rumoured causes for a possible immortality concept surrounding the Five Elders. Some say that it has something to do with the ‘National Treasure’ of Mary Geoise that Doflamingo hinted at. It is possible that there is something in Mary Geoise that can be regarded as something incredibly rare that only the World Nobles and the High ranking members of the World Government know about. There are people who think it could be something like a devil fruit tree, or an ancient weapon, or maybe even something else. These causes often have their own theories so it is too much to explain in detail right now, but we might get back to those options in the nearby future.
Another possibility is the use of the Ope Ope no Mi that Law currently possesses. Although this theory needs some other factors to be very coincidentally beneficial for the Five Elders, it is definitely possible. It could be that every single member of the Five Elders has underwent the perpetual youth surgery that the user of the Ope Ope no Mi can perform. To perform this surgery, the user of the fruit has to give his or her life. Because of this, the fruit will disappear and reappear somewhere around the world every time this surgery is performed, so in order for all a member of the Gorosei to be subject to this surgery, they had to track down the fruit and train a person well enough with the devil fruit and then convince or force the user to give up his own life, unless they found a way to keep the fruit user alive or resurrect the user after each surgery. This process would need to be repeated until all members of the Gorosei had undergone the perpetual youth surgery.
If the Gorosei are actually immortal, it would enhance the whole storyline revolving around the events of the Void Century. If the Gorosei are the actual people responsible for the rumoured horrible events of the Void Century, the war against the Great Kingdom, and the formation of the world-ruling organisation called the World Government, they would enhance the acts of revenge and anger that might result from the finding of the ‘One Piece’ and the Rio Poneglyph.
If this theory is true, it would make a possible final war against the World Government and their leaders a more personal matter because they would be directly fighting the perpetrators of the events of the Void Century, instead of fighting the descendants and successors of the people who committed these acts. This would change this possible final war from a war to restore balance and true justice and peace to the world, to a war with that exact purpose but in addition, it would also be a war of revenge and punishment.
Theory by S.
