Do you think it'll become common knowledge that Aegon is fake (if that's the case) or would it be something that is never explained?
Short answer, I don’t think the public is going to get a chance to
form a consensus. There are going to be enough people who will love the
story and want to believe it that he’ll have a support base, but, you
know, how does he prove this kind of thing? Unless Daenerys decides to
give him the chance to ride one of her dragons. Even that doesn’t
technically prove anything, given the Golden Company’s historical
connection with the Blackfyres, but hey, dragon. Whether he gets the
edge in public opinion depends on who controls the narrative, and Varys
has been setting the stage for Aegon for a very long time.
“A mummer’s dragon, you said. What is a mummer’s dragon, pray?“
“A cloth dragon on poles,” Dany explained. “Mummers
use them in their follies, to give the heroes something to fight.”
(ACOK, Daenerys V)
“At the end a dragon hatches from an egg and devours all of the lions.“
The ending took the puppet show from simple
insolence to treason. "Witless fools. Only cretins would hazard their
heads upon a wooden dragon.” (AFFC Cersei V)
A little more, cut in case you’re avoiding The Winds of Winter sample chapters:
“But that was nothing to the hush that fell over the crowd when she finally removed her helm and named Sansa her Queen of Love and Beauty. In that moment, Elia could not help but feel a sense of poetic justice, as if they were all mummers acting out a distorted shade of that infamous tourney at Harrenhal.”
“You’ll see I’ll bring them back and they’ll be better than ever! Faster,smarter,stronger,completely indestructible.” Douglas say his eyes holding a slight crazed look his face pale. Kara’s warning ringing true “he was losing himself…"his desperation to bring project M-19 and project N-01 back had consumed him.
"This’ll make everything go back to normal.” He mummer to himself going to look at the two large capsules containing a blonde girl submerged in water and a boy the same way.
What do you think of the idea that Stannis is the third head of the dragon? That Melisandre is both right and wrong.
Naw. The “slayer of lies” segment in the House o’ the Undying makes it pretty clear that like the “mummer’s dragon” (Aegon) and the master of the dragon atop the smoking tower (Euron, Dragonbinder-bound Rhaegal, and the Hightower are my guesses), Stannis is a pretender to prophetic destiny. Melisandre, despite her genuinely heroic endgame of throwing back the Long Night, is herself pretending to more certainty and metaphysical wisdom than she actually possesses, as is confirmed in her POV chapter; I think her hubris is setting her (and Stannis and Shireen) up for an unambiguous fall.
The ironic/tragic core of Stannis’ character is that despite being IMO the best man for the job, despite having come North and declared war on the darkness and (come ADOS) proven willing to sacrifice his Nissa Nissa, he’s just not the messiah. Same way that for all Quentyn’s on an (ostensibly) exciting quest to marry the beautiful princess, and for all that he dutifully carries out the proper steps despite loss, horror, humiliation, and ultimately unimaginable agony and oblivion being his only rewards, he’s just not the hero.
FWIW I think the three dragonriders upon endgame are Dany, Jon, and Tyrion.