Finally thank you! It makes me sad and a bit angry when people just say Cheol is a coward or is just a little bitch. Like come on people, THINK, can't you see how Cheol is so big and muscular and yet not once did he attempt to fight back? It's literally because he's already so broken down by the constant abuse. Like damn man, he's been abused ever since he was able to think. Constantly made to think he was useless and stupid, and constantly getting deprived of love and affection. All his life he still wants to get those things, that's why despite having such exceptionally high grades already, he still thinks he needs to study harder. That's why despite being treated poorly by his family, he still works hard to gain their approval someday.
Some people would've already killed themselves if they were in Cheol's position. But Cheol endured, because he wants to live, and he wants to be loved.
I personally had interpretated his reluctance to leave not out of sheer stupidity but an inability to do so, if you were conditioned to believe hiding is the superior means of escaping pain than running become a pointless struggle. Years of abuse isn't something you shake off in moment of convenience but something you are forced to navigate your entire life around. "Why didn't he just leave? " he don't know how.
Cheol also had shown again and again how desperate he is of his parents approval. Maybe the reason why his feet is rooted to the ground is because he's still waiting to earn his place at the table. He craved the warmth for so long it consumed him, see it reflected in their eyes but never at its receiving end. Longing aimlessly hopefully tirelessly for love that would never be his.