Bride of the shadow king

A stunned princess, A reluctant king, A marriage that could save both their kingdoms but destroy their hearts

Through she is the eldest daughter, princess faranie lives in the backgrounds stunned from court and kept out of sight. Her chronic illness make her a liability to the crown and she learned to give place to her beautiful, favorite sister in all things

When a handsome and enigmatic shadow king comes to seeking a bride, faranie is not surprise that her sister is his choice

Through not eager to take a human bride, King Vor is willing to do what is necessary for the sake of his people when he meet the lively princess IIsevel, he quickly agrees to the marriage arrangement.
So why can't he get the haunting eyes of her older sister out of his head