i never suspected him till you mentioned, wow that would be a bigger plot twis tthan that jinsu was the one that killed her or hebeing the shadow, especially because all the story is kind of telling that but, the shadow treat the princess like she doesnt know her or more like he bilitle her like any other man in this worild, so thats why im not sure is the shadow is jinsu, becasue he would be more active in destoying her like a treat, so your teory actually would be a better posibility
and the older bro, like woman hate the worild too, because he is treated like shit for not having magic powers, he have a more solid reason than any other charaters presented till now
I don't think it is the oldest brother as when he speaks to the emperor, he is unaware why royal scumbag would go so far for the princess, and the country's secret regarding the potion. During the ceremony where sanghee was given the title 'treasure', it can be seen that the oldest brother thinks to himself that the king must love sanghee a lot, and there is mention of him knowing the country's secret regarding the potion. When the emperor asked the shadow how the royal scumbag and his knights reached other countries so quickly (3h by plane supposedly), the shadow was unable to answer. Personally I think this has to do with the secret regarding the potion, also if the shadow were the oldest prince, he would simply tell the emperor that the king's weakness is his immense love for his daughter. I think it is more likely that the shadow is jinsu, or jinsu's friend from before (I don't think they would introduce his character just like that and not mention him again)
Yeah it is the oldest brother
I still can't help but suspect though?
Uh, guys. The emperor's shadow cannot be the eldest brother, right?