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.
