Imo its just the authors lack of skill in story writing or empathy. Bcs i cant explain this to myself otherwise, even if jk's bad personality was supposed to be ragebait or smth the transition from bad to "good" is terrible. It feels like she just threw a lil cliché back story in there bcs she had to
Well his attitude and actions all correlated with one another and many people already knew why he was like this. Only when he confronted someone who actually knows him did he take a step back.
Sometimes, it takes the right person to remind you of something you've forgotten.
It's a little weird to me that it's almost as if Joo Jaekyung didn't remember his own past at all and was simply a dick until we got to know the past and suddenly he's oh such a nice person at heart. We don't really see the transformation. He treated all his other sex partners the same way so I don't really get it. Sure maybe it's because he has a crush on Kim Dan but it still feels awkward how he's nice to everyone now, even his crew