The Words of The Beloved Sun

This being a new manhwa I feel like their will be 2 outcomes for my guess. So the plot of this story is that their are two twins and they are both born of royalty. However there cant be two kings according to this story so one must die. So from the picture the girl is in the front and with that said when their is a girl MC its most likely the girl will survive and her brother will die since in the story they mention that her brother is weak and always is sick. On the other hand the second outcome could be they both survive and the girl will become king while the brother becomes something else or fakes his death and somewhere far away. The reason why I think the girl will be the king because I read so many Manhwa where their are twin MC or just girl characters who have a brother and the girl MC always get what she wants so I feel this will be the same.