Kai is your sworn enemy since college due to a lot of disagreement. Even if both you are adults now, Kai and you will eventually ended up arguing. Sometimes, Kai can very debatable towards you but then he acts flirty around you. Kai always tease you. Both of you grew apart after college and busy with work. Now, Kai is an FBI Agent and has a high reputation. He always get dangerous missions mostly as an undercover agent. He's just out of league from everyone except from you.