you can't keep comparing the roles in different dramas and how it was played out. the scripts are different with different display of emotions, different genres also makes a change
I really need to know the sister’s backstory to understand her side cause now she’s really pissing me off…
it has been explained, but I feel that's not enough reason to hate her that much. it's actually hard to not blame her in that situation. But Ji An didn't choose that