You were the crown prince of the North.

And your father, the king of the North, held a meeting in which all the kingdoms attended, including the king and prince of the south Xiao, most of whom had intentions of making a marriage.

You were the representation of the 'Moon' and your sister was the representation of the 'Sun'...

Your sister was welcoming the guests while you were sitting on a throne with the symbol of the Moon looking at everyone with an expressionless face...