Yeshin is actually the mistress son, and hangyeol is the legitimate child Basically what happened was that when hangyeol was born but he had some complications and a low chance of survival, their father along with the grandpa, decided to switch yeshin and hangyeol at birth because they didn't want to lose a legitimate heir, neither of the moms knew iirc and hangyeol suffered bullying from a young age both from his family and classmates Ofc hangyeol starts to feel resent for yeshin, since he lived the life that originally was meant to be for him, when yeshin confronts grandpa and dad both of them tell him Is thanks to the switch he was able to live a comfortable live
Yeshin is actually the mistress son, and hangyeol is the legitimate child
Basically what happened was that when hangyeol was born but he had some complications and a low chance of survival, their father along with the grandpa, decided to switch yeshin and hangyeol at birth because they didn't want to lose a legitimate heir, neither of the moms knew iirc and hangyeol suffered bullying from a young age both from his family and classmates
Ofc hangyeol starts to feel resent for yeshin, since he lived the life that originally was meant to be for him, when yeshin confronts grandpa and dad both of them tell him Is thanks to the switch he was able to live a comfortable live