I don't blame Zhai Xing for believing him when literally everyone involved confirmed that Bo Wang was guilty.…
Try to understand the Bo Wang character better before you decide to hate him. Do not listen to his words and watch his actions superficially. There's a reason for everything he does and it's not for himself.
...have a motive or endgame or is he just a sadistic and paranoid sociopath?
I've always assumed that wolf boy is just like one of those Tarzan characters. Never had I imagined the Emperor and princes are based on real life historical figures. This is such an riveting discovery for me and gives me a totally different feeling for the Bo Wang character because he was real (though not as depicted in the drama).
This is one of those dramas that re-watching is better than watching the first time because one would pick up more of the nuances that one has missed in the first viewing. I love the Bo Wang character in my first viewing. Now it is more than just love: I think of him while I sleep, while I eat, while I work, while I watch other dramas. Wang Dalu makes it even more irresistible; he's one of the few actors that looks so manly with his tan skin, strong muscles and those sexy lips.
She knows that he is lying - watch their eyes. The acting by the OTP is very good because they both say one thing…
All I can say is, hating Prince Bo makes one miss out so many of the subtleties in his expressions, and nuances between him and Zhaixing because our eyes become clouded with hatred; we can't bear to see him every time he comes on screen, we fast forward. We may not even know what we're missing out. What a pity!
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By the way, just curious, are you watching it raw? Nothing implies here. Just asking :)