Family did some sort of ritual to make a god posses the ML to bring fortune to their family (which is why he was kind of hallow and empty during childhood) but since such act is taboo it is going to grant punishment on them, so they adopted MC to make him absorb all the misfortune which is why he gets sick alot.
the so called god gradually took root into the ML body and that's when he started molesting MC in his sleep (wet dreams) ML was obsessing over mc because he is the only one that actually linked to him (misfortune absorber).
When MC said he wanted everything to disappear ML used his power to kill all the family members because he doesn't consider himself as part of them.
At the end MC understood that ML is a god/nonhuman in human body and doesn't care about the money or fortune that the family wanted, but what ML actually obssesd with was HIM the little brother/only one he considers as family.
Now I just got it thanks
guys I’m confused someone explain pls