There's a reader-theory, though, that Aegon is actually a Blackfyre heir (and probably Illyrio's son) and not a Targaryen. Some evidence for this theory:
The Golden Company, a mercenary group founded by Blackfyre survivors with the express purpose of eventually seating a Blackfyre on the Iron Throne, is supporting Aegon's claim.
Although we're told that the Blackfyre's "male line" has died out, the odd specificity of this statement combined with the physical description of Illyrio's late wife seems to imply that the female line survived.
The backstory of Robert's Rebellion suggests that Varys was feeding King Aerys's paranoia by claiming that Prince Rhaegar was attempting to organize lords to help depose him. This probably played a role in ensuring a violent transition of power, eventually eliminating (almost) the Targaryen line. If Varys is a Targ loyalist, this seems like a pretty bad move; as a Blackfyre supporter, though, his actions make perfect sense.
None of that is new, but yesterday I was rereading A Feast for Crows and found a passage that seems to foreshadow Aegon's appearance in ADwD, specifically supporting the Blackfyre angle. In Brienne 7, Septon Meribald explains the history of "The Old Inn:"
"...He forged a new sign for the yard, a three-headed dragon of black iron that he hung from a wooden post. The beast was so big it had to be made in a dozen pieces, joined with rope and wire. When the wind blew it would clank and clatter, so the inn became known far and wide as the Clanking Dragon."
"Is the dragon sign still there?" asked Podrick.
"No," said Septon Meribald. "When the smith's son was an old man, a bastard son of the fourth Aegon rose up in rebellion against his trueborn brother and took for his sigil a black dragon. These lands belonged to Lord Darry then, and his lordship was fiercely loyal to the king. The sign of the black iron dragon made him wroth, so he cut down the post, hacked the sign to pieces, and cast them into the river. One of the dragon's heads washed up on the Quiet Isle many years later, though by that time it was red with rust."
Targaryens use a red dragon as their sigil; a black dragon is the sigil of house Blackfyre. After their defeat, the Blackfyres were diminished in number and forced across the narrow sea ("[he] hacked the [black dragon] to pieces, and cast them into the river"). Could this passage foreshadow the reappearance of a Blackfyre heir ("one of the dragon's heads") on Westeros's Western shore, whom - given the amount of time since Blackfyres were defeated - everyone takes for a Targaryen instead ("by that time it was red with rust")?
I think this is a definitely one of those clues and I think it's about Aegon. I could be wrong and wouldn't mind if Aegon was the 'read deal'.
Edited by House Mauldania, 02 March 2012 - 07:07 PM.