THIS IS ONLY MY THEORY,
i think the ml who did that cruel thing to lamia brother is the past him (exactly before he met lamia). after that incident, it was told that he has sudden change of his personality. maybe, he reverse the time after the past him did to lamia brother.
its make sense right? im not good at explaining things ლ(´ڡ`ლ)
but if it was the past him than why did he attack her brother? in the first life he didn't hurt him so why in this one if everything to this point sould have been the same?
if you know what i mean
umm, actually we dont know if in the first place he do the same thing to her brother or not. the story plot is his childhood, the time when he was cruel, he fell over heels with lamia, lamia dead (i forgot why is she dead lol), he went back in time, and blablabla.
maybe when they love each other, lamia had forgive him or as you say that incident didn’t happen at all. right? ヾ(❀╹◡╹)ﾉ~
This is not okay until we get an explanation for why he hurt the brother so much... (︶︿︶)＝凸