Responses
I think it's mentioned that their mother was a concubine and she was framed for something, so her life was tragic and her death was questionable as well. I think he's getting vengeance for both his mother and dead twin?
It's based on real person but he actually don't have a twin, that's just that drama's plot, right?
So in that drama, one is the prince, Lee Yoon, and another is the abandoned twin, Lee Gyeol. And the plot here is that the real Lee Yoon was killed and Lee Gyeol will pose as "Lee Yoon", and takes the throne. So the tyrant king is actually Lee Gyeol, am I right? Have they mentioned yet why the supposedly peaceful commoner Gil Sam turns into a tyrant?