not to mention the chasm sized plot holes like how does his brain know how to swim but his body doesn't? also if his body did original speak the busan dialect why wasnt he speaking it when he transmigrated if the body familiarity is prioritized over the mind?
Yup it's stories like this I just gotta turn my brain off for hahaha
1. his body is traumatized. Consciously, he maybe different than og Hajin, but body wise, he's Hajin. So if og Hajin can't drink, eat spicy food or is traumatized by water, then so it'll be.
2. The body prioritize familiarity, sure. But it could also be because, og Hajin could have stop speaking Busan dialect since long ago. Seeing as how nobody is pointing out that he has stopped talking in Busan dialect. It must mean that the family forced og Hajin to drop the dialect and develop to fit the standard instead, which isn't all that surprising from what we have seen so far.
Honestly I think it's hilarious that the one who was supposed to be the abused bottom is now turning into the yandere top lol