This drama is one hot mess! Genre, Characters, Story it's all over the place! 

Who do you think is the biggest bi***, as****, or jerk in this series! 

Tough question. 

ChunHui's hubby? ChunHui's partner in crime? Louis? Pervert "art" director Go? ... curiously all male.

Or the writer opting for lots of nonsense (the chance of the step sister being similar to a passing by Korean student in France! the chance that Incheon airport be empty! the chance that tons of ex boy/girl friends end up living in the neighborhood, ...)?  

Definitely Louis. The fact that he introduced his "sister" to Henry, it is just unforgivable. At least Chun Hui's husband loved and took care of his kids.