Responses
I didn't say he has to be your typical 'perfect' pure hearted MC.
He can totally have flaws, but he doesn't have to be an asshole
He could be prideful, envious of everyone around him, greedy, a drunkard, quick to anger, fuck boy .... , any combination of these flaws can make him more relatable yet not a straight up asshole.

I really wanna like this manga (I live the concept of the hero and his teammate)
But I can't get past the fact that Kaine is a terrible person, he's only tame now because he's weaker. And I don't think there's a way to make him out as the misunderstood character (he's simply an asshole)