I think he’s mean because he remembers his dynamic with Lee muhan from his old life. And as he said in the last panel, Lee Muhan was a 15 year old, while he was in his late 20’s. So for modern Ja-heon, Muhan “took away” his Mugo’s and he can’t get them back + he reminds him of his inappropriately clingy (and kinda pathetic) junior yk ?
He doesn't remember his dynamic with Lee Muhan in his past life, that's why he asked in this chapter, and it was also shown in previous chapters. He's been mean to Muhan for like 4-5 chapters now
It is probably due to his past dynamic with Lee Muhan indeed, but he doesnt know that
And for the Mugo part yeah thats what Im saying, he doesnt know about DID so he doesnt realize how incredibly harmful and counterproductive that is
I know he doesnt know DID but being mean to one of the alters is one of the WORST things to do and I feel so bad for Lee Muhan omg remember alters are FRAGMENTS of the system, meaning they are ALL part of the same ! Be nice!