
Tia changed coz she returned to the past while keeping her memories....but he can't change easly like that....poison can't change a personality come on ! for myself if I return to the past I swear I will never date my ex ...selfish bastard ! he just dumped me he didn't kill my father or made me lick his shooes or destroyed my house ..but the day I see him I will change my direction

I'm just gonna say what I know so I can hopefully clear somethings up. As seen in my other comment the prince didn't kill her father. But that's just making him less of a bad person by a bit. Some medications could change a personality but I am not sure if it would be similar to poison. I remember a flashback in the prince's POV where it is seen where the prince is jealous on how our mc got like more attention by his father. It was also stated that he thought " If you like her so much why don't you just make her your heir? " . That could of changed how he thought of the mc a bit seeing how he was envious of her. The prince married Jieun I think was her name because he thought she would love him. That kinda shows how he could me a lonely boy or simply someone who yearned for love. This could be a reason for his personality in the other timeline. In this timeline he got love, his misunderstanding was also cleared. This is simply what I think if there's anything wrong please feel free to tell me.
ugly bitch and it"s not about her face ! her character sucks.. she doesn't deserve their true love...poor boys.