Was Kirei a good guy or a bad guy?
I don't know, but I'm sure he was the best girl.
What would Kirei be classified as by modern psychology? A psychopath?
He'll team up with Shirou, challenge Julius to a cook-off, and defeat him with the best Mapo Tofu ever conceived.
Very classical sociopath, I guess.
Someone who "violates the social norms of morality" might describe it even better.
He's not really a psychopath by definition. More like a sadist with a twisted sense of morality.
Sadist with clear identity issues. He realizes what he enjoys (people's suffering) is completely immoral and feels guilt over it. That's a trait sociopaths usually don't comprehend or feel. He also doesn't really exhibit impulsive behavior for immediate self-gratification or harbour the desire to dominate and control people.
What exactly makes you consider he's a good guy? How is that even a question?
Because martial arts.
He's a villain who can't help being good since he spent his entire life helping people. He never really goes full villain in any scenario until the protagonists make it clear they aren't going to let the grail give birth to his evil fetus thingy.
>So I told Kirei to betray Tokiomi... he actually did it the absolute madman! hahaha!