I love this argument!!! Vayne is evil. He is a warrior turned politician. He spent his life working for a goal of power. The fact that he has a loving little brother eludes to him being a caring individual. It's when he came to true power that he had politicians whispering in his ear about what to do (Cidolfus Demen Bunansa) and how to retain that power. The true evil is Venat, but for every gun, there is a bullet to act through and that happened to be Vayne.