These are the things(exept for One Piece) that we know very few things, close to none at all.
In noticed that those who bear the will of the D. don't abide to the WG rules
Garp doesn't really care, if Sengoku didn't stop him, than he would've killed Sakzuki and after the war he quit the marines.
Roger became the pirate king, someone who was a great threat and problem of the WG
Ace was the same, so is Luffy
Dragon is the most wanted man in the world, a revolutionary and also a man that hates the WG very much and tries to destroy it.
Teach took the position of Shichibukai only to take over the new era and kill Whitebeard, after that he palnned to dedstroy marineford
Rouge was also against the WG, just by giving birth to Ace
Saul also didn't accept the orders of the WG to destroy the Ohara's and destroyed 6 warships
All of them didn't or don't aprove to the WG methods and some of its rule.
We all know that about 800 years ago the WG ended the void century and took control of the world, all the history of the void century is unknow to everybody, only the Rio Poneglyphs has it written.
Most poneglyphs have written on them the location of a ancient weapon.
The ancient weapons are weapons built by an ancient civilization(most likely from the void century)
We also know that the Poneglyphs were built by the same ancient civilization
If the poneglyphs and ancient weapons were built by the same civilization from the void century, just as Robin said(if I remember correctly) that those were the lsat messages remaining from the void centruy.
Now this si where the fact stop and I begin to imagine:
The ancient civilization that created the weapons(I'll call it Byuzarea), Byuzarea fought with the ancestor of the WG and built those weapons to defeat them. There was a great war and the situation seemed hopeless for the Byuzareans so they left 3 important things for the next generations of mankind: Poneglyphs, their message wirtten there with ancient weapons, the means to try and stop the WG, that would be the reason why the WG banned their reading, but couldn't destroy them so they hid them. The WG somehow made it like those people and their civilization never existed, not to reaveal what happened. I don't know what happened either and can't even begin to imagine it at all, maybe they were cruel, maybe they were alines, WHO KNOWS?
But the Byuzareans left their message and I believe The Will of the D.(that's why one of the gorosei said it means danger, for it is dangerous for them). This will manifests itself subconsiously with the power to change the world. The peaople that posses it with whatever personality will become great men(women) and change the world, bit by bit. These people's will is the strongest(just like the genes, its like the byzareans left modified them genetically to become great). That's the reason why they all opose the WG in one way or the other and it's not like Garp actually did what the governement told him, he just followed what he tought is good on what he tought was the good side. Well I don't know for sure for what the D stands, but it might be for the name of the civilization(that's why I gave it another name:))) ). After the SH find One Piece they understand the reason for many deaths and the existance of despicable people like the world nobles, than they'll reaveal the true history to the entire world, it will be war, those who are on the WG side and those who are on the side of the SH.
I won't develop it anymore, because I don't want to make it how I imagined all of it, but more like an opinion of what happened
Now I want to hear YOUR opinions about when you try to connect these dots.
Thank you for reading this.