This is what Junseo needed to realise instead of trying to be Ajin's saviour.
She didn't turn out the way she did because he froze while his mom tried to drown her. Nor is it even his mother's fault. Her neurological wiring was already set before he met her, all the evidence shows that disorders like ASPD aren't solely caused by environmental factors but that there is a genetic component to it. He was clearly very traumatised by the incident & she milked it to manipulate him thus why his entire life's purpose became "protecting her". And that's the irony , because even with all the remorse and compassion Junseo is capable of feeling for Ajin's collateral victims, he still would've never have exposed her if she hadn't been the one to cut him off first and leave him without a purpose.
In the end, he's now a better person without her influence, as he gets to reinvent himself and right his wrongs but she'll always be the same with or without him.
I have a feeling he doesn't end up like chapter 1 showed because of ML . I'm worried these hedonistic guys having the orgy will be the ones to assault MC as revenge or something. The last thing he needs is more trauma though