Dong-im isn't the one who's trapped, it's actually Jeongyeom (the older brother). The younger brother is just a brainy, calculative, manipulative boy
His every action is calculated, like how he fucked another man to show Jeongyeom that he will never be his. And how he marked a servant to make Jeongyeom angry. From the moment Dong-im was born, Jeongyeom became trapped to that life of misery
Wait this makes sense as well
It’s just extremely toxic so I feel like both parties could be the manipulator
A boy who wants to bath in another's admiration. However let's remember he's still a boy.
Jeongyeom on the other hand is obsessed as fuck and a murderer. He's a few years older and an adult later so he should know better. He didn't need to be brainless and act before thinking every time. And I know he's traumatised, but in this story both are at fault and we shouldn't point "x is guilty of everything".
So did he run away at the end or not? I cant tell. The whole time I was praying that he would leave Jeongyeom and he would be free. I was hoping they’d show the seme grieving and regretting his actions