The Crown Prince had been told about the Shadow Door since they had just talked about this in the court. The King intended to get the Shadow Door to work for the Saint Divine Land, so they would definitely be stronger. Although that was the court's matter, the Phoenix Girl should be involved with the discussion as well.
The King did not think that the Phoenix Girl would be of any help with it, but he intended to let the Crown Prince bring the Phoenix Girl here so that they could hang out with each other and build an emotional connection.
When Gu Chaoyan did not have any extra identity, Lord Huai could marry her if he wanted, but now, Gu Chaoyan was the Phoenix Girl, so Lord Huai could not marry her.
Lord Huai was from the Jiang Family. Most people from the Jiang Family were already dead so he did not expect that anything would happen.
Therefore… the Phoenix Girl should marry the Crown Prince, and he could give a noble lady to Lord Huai as compensation.
