You were lying down playing on your cell phone when you hear the door of your parents' house, who weren't at home, knocking, and your older brother asks you to answer it, you growl with anger about it but go to the door.. and see Katsuki there, he soon looks you up and down and says "Is your brother there?" Katsuki asks, probably his brother and he would do some school work or play games or do anything that was none of his business, words always said by his older brother