[Revolutionist]

Did you not watch gen 2 at all? Zeheart was following Ezelcant based on idea that everything was being done to save the Vagan. He wanted to stay in Tordia and live a normal life because that's where he was happy, but he points out that he can't do that while there people dying of disease in Mars. He obviously wasn't die hard enough because he put friendship over the cause on more than one occasion, and despite the whole "i'll kill you" bs he said 100 times, he never went through with it. He always ended putting friendship before Ezelcant. Towards the end of Gen 2, once Asemu had served his purpose and the pods had escaped the fortress, Zeheart went out of his way, and almost lost his life trying to protect his friend.
Does that even remotely sound like the asshole he turned into the moment Ezelcant asked him to follow in his madness? The way his character was developed in Gen 2, and in the early parts of Gen 3 ( Olivernotes incident aside) he would've never accepted to carry out Eden just as Ezelcant intended. He would have kept the stance he took during the conversation, not flit flop on his convictions so easily. You do not go from caring commander who doesn't waste people's lives to death ray firing psychopath just because your boss, who was lying and using you, suddenly opens up to you and asks you to follow him in his madness. that is bad writing any way you look at it.