We always encounter characters who have impenetrable walls, is protected everywhere, doesn't care what happens to others and look like they came to this world for fun, type of psycho male leads, or side charas.. (the type where you think that the only way to get rid of these type of people is to out yourself, because you can't do anything against them.. the type where you feel like even Satan would be scared, the type even the most pure soul come to ask how these type of psycho still alive and they shouldn't have come to this life)

İ have never encountered a manga manhwa manhua or webtoon etc. With characters who were able to overcome these types of charas by themselves..(especially by themselves.)

So if you have any recommendations with charas who were able to overcome, please do so.. especially if they are isekai. Anything is allowed.

Your description made me think of Dark Heaven. The antagonists in that are scary!
It is BL and not an isekai so I'm not sure if it fits. If you give it a try be warned, it is not for the faint of heart and slurs are abundant.

i will take a look, but it doesn't have to be isekai, just that i welcome them... thanks and if you have more , please write.