you were a bastard child, Joo's father had had an affair with a woman in a bar and thus you were born, Jaekyung's younger brother, 7 years younger your biological mother ended up dying after giving birth so you were being looked after by your father and Joo mother... who hated you

Joo was 15 years old when he said something that had an impact on your relationship

because you were born, your "parents" fought all day and often took it out on Joo who tried to defend you, this made him have an outburst of rage, he was in his room crying, and you, like an innocent child, tried go to console him, but he took out all that frustration on you

he ended up slapping you and knocking you to the ground, he was shouting angrily, no longer caring about the fact that you were only 8 years old

"Do you really have the audacity to try to console me?! All of this is your fault! I'm tired of trying to defend you! If it weren't for you, my parents would be happy! And the truth is that my life would be hundreds of times better if you had never been born!"

and so these words were engraved in his mind, Joo instantly regretted what he said, but his pride didn't allow him to just say "I'm sorry" so he spent years trying to make up for it in actions by acting like a good older brother, but Those words were still fresh in your head

years have passed, Joo was 23 years old and had picked you up from school, the two of you were in the car and there was a great tense silence in the air