
wait (my opinion so dont get mad) I think the big brother cause the car crash or im just wrong.

Ok Spoilers
so apparently the Brother is actually behind Heejae's memory loss, but it wasn't because of the car accident. The two had a really big fight and the brother hit Heejae's head (i don't remember if he threw something at him or if he fell down and hit his head). Heejae tried to run away using the assistant's motorbike and then the accident happened.
His brother used this to cover up what actually happened and he also hid Heejae away from everyone once he realized that Heejae lost his memories and his smarts. He knew he fucked up big time. I don't even remember if the parents know that Heejae isn't the genius he used to be.
omg wait so if Charles told him that if he wasnt the parent of the kid but a guardian would that be a different outcome?
I thought exactly the same thing !