Interesting! I had to read up on him, since he was supposed to have been killed by Gregor Clegane, who admitted just this while fighting Oberyn Martell. He said he killed the baby, raped and murdered his mother.
However, Tyrion met a man on board a ship who claimed to be Aegon. Supposedly, Aegon the infant was switched with a tanner's son whom Varys had purchased for a jug of a special wine. Before the Lannisters could get to them Aegon was spirited away.
I think this makes a lot of sense, since that is JUST the kind of thing Varys would do. And it's a small hint that GRRM could have dropped. Third Head of the Dragon?
He hasn't played any role in the books or show as of yet, except the few sentences. I'd like to think the GRRM would have spent a little more time with him, but then again, it may be just like him to drop that nugget and then make you forget about him.
Doesn't make you want to feel for the character when you don't have a chance to get to know him, though.
Sigh.
It's a very interesting part of the story, he did purchase the child for a jug of Arbor Gold wine, a leather tanner had never tasted Arbor Gold before, and switched the leather tanner's baby with Aegon and smuggled Aegon out of King's Landing.
I wish I could find the citations for this but something about Arbor Gold wine is supposed to represent lies (any time its served or drank in the books the contents of the conversation are almost always lies). So its sort of meant to be a nod to "this isn't actually Aegon". He does have the features though, the purple eyes and silver/fair hair when its not died blue. Its likely he's a Blackfyre.
(from a Wiki of Ice and Fire)House Blackfyre is an extinct noble house from the Crownlands. A cadet branch of House Targaryen, House Blackfyre was founded by Daemon Blackfyre, a legitimized Great Bastard of King Aegon IV Targaryen. House Blackfyre is named for the Valyrian steel sword of the same name.
Further important information to this:
War of the Ninepenny Kings
Main article: War of the Ninepenny Kings
The last attack of the Blackfyres occured when Maelys "the Monstruous" Blackfyre, head of the Golden Company, joined forces with a number of ambitious men and eventually invaded the Stepstones in 260 AC as a base for a future invasion of the Seven Kingdoms. King Jaehaerys II sent an army that defeated the rebels.[9][7] Maelys I was killed in single combat by Ser Barristan Selmy, who cut a bloody path though the Golden Company's ranks to get to Maelys.[10]
According to Illyrio Mopatis the Blackfyres were extinguished in the male line when Maelys Blackfyre was slain.[11] What happened to the female line is currently not known.
They seem to want to ignore Aegon and Jon Connington though in the show... Which is a little sad because they just killed half their cast in a single episode. So maybe Aegon will still make an appearance. The Golden Company was friggin cool, all former commanders get their skulls dipped in gold and placed on their standards, maybe they need to tell HBO they don't have to use actual real gold skulls while filming.
As for the whole "Dragon must have 3 heads", in the books its a bit more obvious that Jon, Dany, and Aegon (doesn't matter if he is a true Targaryen or a Blackfyre from the female line) would be the 3 heads of the dragon. Between a guy who has Lannister features, and a guy who has true Targaryen features I'll put my money on the one with the purple eyes and silver hair as being the Targ.