Wtf, Vayne was lame as fuck His ambitions were hardly his own. Venat was the one who influenced him to seize power and was the one to give them the knowledge of the stones of power. Pretty sure Vayne was nothing more than a mere puppet in the grand scheme of things. He couldn't have gotten as far as he did without Venat intervening.
Now Gabranth. That was a man with a motive.
Vayne literally couldn't even see or hear Venat until after Dr Cid died
Also the story makes a bit more sense if you think of it as a WW2 analogy.
Vayne = Truman, Dr Cid = Oppenheimer, Nabudis = Hiroshima, Ashe is the representative of the conquered Japanese national spirit who goes on this revenge quest to acquire nukes (nethicite / deicite) and finally gets them but ultimately chooses not to use them because it's wrong and achieves her victory some other way.
the occuria is communism of which the fear of it is why Vayne and Dr. Cid deployed the nethicite in the first place.
But it was Venat who showed Cid how to make nethicite and the Vayne and archadia in general seemingly had no ambition until they knew of the stone and its power.
I mean, about 5 years prior to Cid making contact with the occurria Vayne had already killed several of his siblings who had started an uprising. So there's a chance that he had decided to set his eyes upon the throne at that point. The judges and Vayne speak in-game at least twice of how there had been battles between members of House Solidor, and that by the events of FFXII proper, it was just the two of them. Since it was about 5 years after Cid and venat hatched their plan but 10 years after Vayne first started to kill rivals for the throne in the name of the empire, well. Two birds, one stone, ramp up the timeline. And then by xii proper, events made it so he couldn't wait any longer for the emperor to pass, and he had to do so before the Senate could appoint Larsa as members who supported Larsa usually did so because 1) he's innocent, hadn't killed siblings, might be a good leader or at least not bloodthirsty 2) young and naive, easy enough to control 3) young and inexperienced, meaning a perfect chance to pursue their own goals in the years they would have been acting more in place of him as a proper leader
And we all remember how vayne blamed the emperor's death on the Senate and had them all killed. ---
