wonwoo is mingyu's older brother

mingyu is wonwoo's adopted, autistic younger brother

wonwoo knows what is love, mingyu doesn't 

mingyu knows how to go to the treehouse when they are in trouble,

wonwoo doesn't 

wonwoo knows how dangerous it is to have a phone conversation while driving,

mingyu doesn't 

mrs jeon- everybody knows wonwoo loves mingyu,

mingyu doesn't.