He was given up the moment he was born simply for the fact his mother was an idol who'd gotten pregnant, and his father had left, not wanting to care for a child, as he was another idol.

     Idols aren't supposed to be married or have relationships, so an agreement between his parents and the company was made. If they hid the fact she'd gotten pregnant and had a baby, and had had a romantic/intimate relationship, then she and her partner could remain as idols. So, she gave birth to Jaehyun, then she'd given him up for adoption, just so she could continue to be an idol.

     So, Jaehyun was placed with foster parents as an infant, and he stayed with the first family for five years. However, at five years old, he developed a serious illness, and his family claimed they couldn't afford him anymore. They left him at the hospital and took off, and no one was able to find them after that.

     So, the hospital staff had a five year old boy with cancer to take care of. A boy that didn't have any way to pay for his medication or treatments or anything.

     Jaehyun was placed with someone willing to take care of him up until his treatments were over, and when Jaehyun was six, he met Daesung, a cancer buddy, and someone who also had no parents. The two of them, though very different from each other, became close friends. Jaehyun and Daesung were even born on the same day, at that.

     Jaehyun was always one to see the negative side of everything, whereas Daesung saw the bright side in everything. So on days when Jaehyun especially felt sad, scared, worried, or depressed, Daesung always did his best to cheer him up. 

     After a couple of years, he started to do better, but then his cancer came back and was even more aggressive than the first time. So he was placed back in the hospital, and with Daesung again, at that, who had not yet gotten much better. Daesung had gotten to go home shortly before Jaehyun, and they ended up together again. 

     Jaehyun's new foster family had to give him up, as it was found out that they were not the best of foster parents, as they'd claimed Jaehyun was well now that he was home and hadn't furthered his treatment, which led him back to the hospital. He and Daesung were both parentless once more. 

     When they were eight years old, Daesung and Jaehyun were both adopted by a Christian American couple, and the American couple stayed in Korea so they could get treatment without having to worry about finding a new doctor or hospital for them. They also didn't want the stress to make the cancer worse. 

     Finally, at ten years of age, Jaehyun and Daesung were doing so well that they didn't have to go in as frequently to see the doctor, and they were soon given their very last treatment. The adopted boys, who were as close than brothers or closer by this point, moved to LA in America with their adoptive parents. 

     Jaehyun was finally told why his parents didn't want him when he was thirteen years old, since he was curious and he really wanted to know. So, he was told the story, and it cut deep into his heart like a knife. Daesung, after hearing the story, shared his own story with Jaehyun. The two became closer and closer to each other.

     Jaehyun auditioned so he could be a part of Hollywood Arts, since he and Daesung thought it would be cool to be actors, maybe even do some singing— so long as they were nothing like idols, of course. Jaehyun honestly despises idols with a passion.

     So, when he and Daesung were sixteen, they were accepted into Hollywood Arts.