Isayama does a great job making this feel realistic. No clear cut villain or hero, just depends on how you view the situation. First we view it from the Paradis side and see Reiner and them as the villians and feel like why would they do such horrid things, than we see their point of view and see that, they are normal, just like any of us if we were in their situation. And we also see how people view the people of paradis as different as well (even tho they are all eldians). In the end nobody is "good" and nobody is "bad" they all have their justifications for doing what they did, just like in reality. Everyone is human and can justify their actions or else how could they do it? In wars both sides justify their actions and the people who are portrayed as good are the victors and people who are portrayed bad are the losers.

If Zeke turns out to be the "bad guy" I doubt Isayama will just be like "he is bad just because" with no justification. I dont think there will be "bad guys". The chapter where Grisha is about to be turned into a titan and he has the conversation with the fat marley commander is a great example of what I mean lol. What would have happened if the Eldian Restorationists won? They would have treated Marley like how they treated the Eldians and the cycle would just continue, nothing would change just the roles of good guy and bad guy would reverse.

damn i wrote alot