"I dreamed it. This pale white castle, you, a dragon bursting from an egg, I dreamed it all, just as I once dreamed of my brothers lying dead. They were twelve and I was only seven, so they laughed at me, and died. I am two-and-twenty now, and I trust my dreams."
From the end of the story, it seems rather clear that the "egg" in question is none other than Egg. His resourcefulness -- even when quite ignorant of what was truly going on -- was surprisingly shrewd, and he showed unquestionable courage. Bloodraven clearly assesses the boy in a new light.