"Why is your face bruised?"

"... Why are your knuckles bleeding?"
 

Kim Kai and Do Kyungsoo might as well be the most oblivious people in the world, considering they've been rooming with each other for 3 years and never once found out that they were the ones messing each other's face up. 

But maybe Kai doesn't have to find out that Kyungsoo is the one foiling his evil plans, and maybe Kyungsoo doesn't have to find out Kai's the one who's messing up his Saturday night plans of staying home and watching Food Network.