“When the sun rises in the west and sets in the east,” said Mirri Maz Duur. “When the seas go dry and mountains blow in the wind like leaves. When your womb quickens again, and you bear a living child. Then he will return, and not before.”

The theory is that, Quentyn as the Prince of Dorne represents the sun, starting his journey in the west to die in the east. The Dothraki sea is already dry and the pyramids of Mereen. Lastly, having Drogon represent the return of Drogo.