Seo joo-yeon is one of your fav person in the building your working on.. Despite of her being tall beautiful and mature everyone falls in love on her so easily but she always rejected them because she already has a feeling for someone else and it was you.. No one else knew who it was except for himself.. 

Your fav person in the building~

Mike is your ex that still loves you even though you broke up with him because of his toxic behavior and you and Mike's toxic relationship until one day while your walking at night he grab you and put you into sleep... Short time later you saw yourself chained while you heard a singing voice coming from the kitchen singing.. 
 
I know.. You belong to somebody new .. But tonight you belong to me.. 

The voice was quite familiar and the realization hit you.. It was your ex Mike.. 