A group of adventurers come across a child’s body on their adventures, odd being such a remote location. Their is no detectable sign of violence to the child, nor are their any signs of life. Suddenly the child opens its eyes, looks towards the group and introduces themselves to the adventures.
If this wasn’t odd enough, the child can’t remember where they are from, only their name and age. Stranger yet, the child has a tattoo on their right shoulder of a family crest, to a family that died out over 200 years ago.
The ruling family depends on some magical artifact or place to secure their right to rule. A monarch isn't considered legitimate until he or she has been "accepted" by the artifact or place, whatever that might entail. It is also possible that some one else, not of the ruling family, could be accepted as the legitimate heir... A fact which the monarchs would like to keep secret.