Aemon loves his brother Egg, and his brothers of the Night's Watch. He was once a Targaryen prince, and was once offered the crown... and he's been waiting for the Prince That Was Promised for a very, very long time, discussing the prophecies and portents with everyone from Egg to Bloodraven to Rhaegar to Jon and Sam. I'll also give my explanation for "kill the boy, and let the man be born."