The Gorosei are the heads of the ruling organisation of the world in One Piece, also known as the World Government. The Gorosei are the people that directly control the Marines, Cipher Pol and are also the pact with the Shichibukai. The Gorosei generally rule the organisation that the World Nobles founded, but their position is most likely ranked under the position of the Celestial Dragons themselves, at least officially, but in reality their influence is much higher than the influence of any Celestial Dragon, and they can be seen as the true rulers of the World Government and even the world itself.
There is a certain theory that has been around for a while now and has also known many different ways of interpretation and explanation. The basic concept of the theory revolving around the Gorosei, is that there is a possibility that they are immortal or at least have an incredibly long lifespan that could potentially date back to even the Void Century.
The believers of this theory usually see the Gorosei as the people who were there when the World Government formed and took control of the world, and they have likely been in command of the organisation for all these centuries. Because of this, it is likely that they might serve as the final antagonist of the series, due to their mysterious and likely dark past during the events of the Void Century which has ties to many aspects of the series.
While there is hardly any evidence for this specific theory, there is one thing that many fans take as the prime piece of evidence. During Robin’s flashback of the destruction of Ohara, the Gorosei are briefly shown during the whole ordeal. During their appearance, they seem to have the exact same appearance that they have in the current storyline. Although their appearance is the same and they don’t seem to have aged at all during this period of time, the events of the Ohara flashback and the current storyline are 20 years apart. Because of this, there is a lot of confusion and discussion about the aging process of the Gorosei and the possibility that they could be immortal.
Another bit of evidence that can be regarded as minor when comparing it to the previous bit, is the fact that the Gorosei 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 Gorosei. Some say that it has something to do with the ‘National Treasure’ of Mariejois that Doflamingo hinted at. It is possible that there is something in Mariejois 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 Gorosei, it is definitely possible. It could be that every single member of the Gorosei 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.