yup, my guess that paired with the distress of thinking seunghyun left him behind(my giess seunghyun found him in the shed and tried to get helped, but bec he was a kid himself maybe his brother dragged him out but by knowing seunghyun he wouldnt leave until he is sure the kid is safe). but yeah my bet the babysitter locked him there bec he was pissed at him for not speaking to him with respect.(which, i am no korean but i am aware that they have a similar thing with keigo, so i assume chejun didnt speak in the korean keigo, and thats why he hates him so much, still not an excuse, but like- some kids especially high schoolers or college kids get power trips over this sht, especially if they are themselves are usually get made fun of and talken ti disrespectfully on a daily basis, usually you have those who are just rotten and will look for someone smaller to vent their anger at)

I knew it! i knew it was a misunderstanding on uncle side! theres no way he would do that to chaejun must have been that babysitter. poor baby seunghyun just was hurt and emberassed which is normal in kids, he was just big for his age but he is also a tiny baby here! god i hope seungy in the present i okay and unharmed and i hope this time maybe if he will get him from the shed it will help chaejun's trauma TwT