You're not alone ┗( T﹏T )┛
i read this long ago, so sorry for inaccurate info or if it wasn't the answer you wanted but; namsoo and hyeongoh are twin brothers that were separated at birth. hyeongoh's parents wanted him to major in medical because he has really good grades, but he took up psychology to help with his twin brother, namsoo, who is currently undergoing therapy.
thank you omg
Yeah, I think the beating Namsoo took at the end might have given him severe trauma, if not brain damage that psychologically caused him to revert to a childlike mental state. It's actually a semi-common coping mechanisms for victims of severe mental abuse, physical abuse or both.
I think he's always been like that because of the environment he grew up in. He has no support from anybody. He grew up seeing his "dad" acting like that. Basically he has not been taught whats considered "right and wrong" in society
i don't understand the ending