I'm probably re@ching here but maybe 5ungho fe@rs Joon because of his unsettling presence? Like "badum" doesn't look like something that he likes the guy plus when your heart beats faster more blo0d is rushing through the body so that could explain the blu5hing. Keep in mind that sungho is like incredibly sheltered and the signs of l1king somebody was informed to him by somebody else. Likely meaning he's interpreting this as he l1kes the guy. Keep in mind that this probably a reach lol