"His name is Aegon Targaryen."
The Game of Thrones Season 7 finale was packed with twists and reveals, including the death of Petyr Baelish, Jaime (finally) turning on Cersei, and the Wall coming down. In amongst all of those was the flashback to Rhaegar and Lyanna's wedding in Dorne, confirming they were in love and Jon's the legitimate heir, before the announcement of Jon Snow's real name.
Jon, of course, still doesn't know anything about this, but his name being Aegon throws up all sorts of questions and potential issues. The first is why he has been called that in the first place, given Rhaegar already had a son called Aegon (something Lyanna would've known). It's an odd decision from Lyanna, but maybe that's just what she thought would be a fitting name for a Targaryen boy, and makes more sense if she had heard of Aegon's death before giving birth.
It could also, however, be a sign of the show finally incorporating elements of the Young Griff storyline from A Dance of Dragons. Tyrion first encounters the sellsword Griff and his 'son', Young Griff, aboard the Shy Maid while sailing from Pentos. It's not too long, however, before he deduces that Young Griff is actually Aegon, the believed-dead son of Rhaegar Targaryen and Elia Martell. Griff, meanwhile, is revealed to be Jon Connington, former Hand of the King and good friend of Rhaegar, who was exiled from the Seven Kingdoms and also thought to be dead.
Their initial plan is for Aegon to wed Daenerys, as she has the larger army despite his stronger claim, but ultimately they decide to head for Westeros themselves with Aegon making his own claim on the Iron Throne. The plot has never made it into the show, although we've seen elements of it passed to other characters, like Jorah contracting greyscale while rescuing Tyrion (which happens to Jon in the book), and Varys supporting Daenerys' claim rather than Aegon's.
It's seemed very unlikely since Season 5 - the logical point for him to appear - that Young Griff would ever appear on the show, and this should be a final nail in the coffin. It could, however, hint at a direction for Jon's story to go in, as well as where that character is going in the books.
With that Aegon seemingly off the table, and a romance blossoming between Jon and Dany, it can lead to the original plan for Aegon marrying Daenerys and ruling together, but with Jon instead.
As for the books themselves, it's long been theorised that Aegon is a pretender - indeed, that's what he's pronounced by the Crown when he lands in Westeros - and this is another big signal of that. The character seems more like a stalling tactic or unnecessary diversion than a genuine contender for the Iron Throne, so in giving Jon his name, does it mean that Aegon really is fAegon? It looks increasingly likely.
But the Jon reveal here suggests that we could still see him challenging Daenerys' claim on the Iron Throne though - especially since he's beaten her to Westeros - and how she deals with that challenge when she eventually gets there herself, while on the show seeing her deal with the realisation that 'AeJon' is the real heir to the Iron Throne. Game of Thrones has condensed multiple characters into just one before - e.g. Gendry includes elements of Edric Storm - so there is a precedent for Jon having parts of Aegon's story.
Another interesting wrinkle to all of this is the Golden Company. They're hired to fight for Aegon in the books, but on the show are coming over to work for Cersei. It's a massive long shot, but if there were any last chance of Griff or Young Griff, this would be it. At the very least, we could meet some familiar characters from the plotline, such as Harry Strickland.
Finally, there's also the question of what Jon will actually be called in the books. This could be something taken straight from the plans of George R.R. Martin, but with another Aegon active in his story, it might become much messier than it is in the show. After the Tower of Joy scene last year, it was theorised the name was Jaehaerys, which it could be in Martin's story, while Aemon also feels like a very fitting name for Jon (given Rhaegar at least corresponded with Maester Aemon, while Aemon the Dragonknight was a beloved figure).
What do you think about AeJon/fAegon and how it'll all play out in the books and show? Share your thoughts down in the comments.