Yeah, the older step bro did do shits to younger step bro before. However, the scale from 1 to 10 about what the younger step bro did to the older step bro currently is 10/10 worst than what the older step bro did to him. Some people will say the older step bro deserves it while some people will say that what the younger step bro did was too much. In other words, they don't deserve a happy ending. They are both doing bad things. So, yeah.
Nah, the MC doesn’t deserve a bad ending, yeah he behaved like an asshole to his younger step brother, but he didn’t do anything horrible. As a matter of fact, most of the time he made a fool of himself. In my opinion he needs therapy and after that he is ready to meet somebody nice. ML though is a rapist, he deserves to die.
Author, come on. Just drop the biggest plot twist here ヾ(❀╹◡╹)ノ~. AND I'M NOT TALKING ABOUT INCEST PLOT TWIST SHIT LIKE IN OSHI NO KO (╬ ̄皿 ̄)凸. I meant, make the other dude the endgame, yeah? You know, when everyone though the step bro is the endgame, turns out, it's the other dude. And to make them be together, they need to beat the shit out of step bro first before they can have their good ending?
But I also have this hunch that author won't listen to me. Incest all the way, huh... Haha, haha....