"I'm not stupid, ser." Egg lowered his voice. "Someday the dragons will return. My brother Daeron's dreamed of it, and King Aerys read it in a prophecy. Maybe it will be my egg that hatches. That would be splendid."
That Daeron kept dreaming of dragons -- that it wasn't an isolated event in which he identified his uncle's death at Ashford -- is new and interesting information. Obviously, his dreams relate to the birth of Daenerys's dragons. King Aerys I's prophecy is likely the very same that Rhaegar read, of the Prince who was Promised, which we're told by Melisandre contains the claim that he'll bring forth dragons from stone.