It is diffucult to have a strict father especially when he found out that you have a boyfriend. For Krystal, it's normal and she felt that her daddy, Kai, really loves her. So Krystal's boyfriend, Sehun, he will do anything to impress the 'boss'. 

Meet Wu Yi Fan---Oh,it was now Park Yi Fan but Kris will do,he hated the fact that his mother married with other guy,other than his father.And he hated the fact too,that he has a stepbrother. He wanted attention and love from his mother and new father but he had a stepbrother. But what if,he don't care about recieving attention from his parent and he only care about his stepbrother,he only need his stepbrother especially the love.