Fans of Game of Thrones the show, and even more so fans of A Song of Ice and Fire, the book series, have been waiting for the appearance of Azor Ahai about as eagerly as the characters have. So who is it? Stannis Baratheon? Rhaegar Targaryan? Jon Snow? Well, there's one clue in A Feast For Crows that could hint towards Azor Ahai, and it may not be who you expect.
As Bustle points out, Maester Aemon gave everyone a huge clue about Azor Ahai in A Feast for Crows. He believes "the prince that was promised" to be Daenerys Targaryan. In the books and the show, the Prince That Was Promised and Azor Ahai are both heroes prophesied to be reborn who also eventually save the realm from The Others (White Walkers.) While they are sometimes viewed as separate entities, they are also often taken to be interchangeable iterations of the same hero, just from different cultures. The Prince That Was Promised appears to come from a more Westerosi tradition, whereas Melisandre is eager to meet Azor Ahai, the hero promised by R'hllor, the Lord of Light, whom she worships.
Now, there are a few different theories on who Azor Ahai/The Prince That Was Promised/etc. could be. Keep in mind it could also be that Tyrion is right, there is no Messiah with a fiery sword, and we're all in for a rude awakening. "Prophecy is like a half-trained mule. It looks as though it might be useful, but the moment you trust in it, it kicks you in the head," he remarks at one point.
The prophecy states that The Prince That Was Promised/Azor Ahai will be reborn amidst salt and smoke under a bleeding star, will be a descendent of House Targaryan, will awaken dragons from stone, and, rather obscurely, the "dragon will have three heads." Very few fans of either the show or the books agree with Melisandre that Stannis Baratheon is Azor Ahai reborn. Maester Aemon's theory, however, has far more supporters amongst the Game of Thrones obsessives.
In A Feast For Crows, as he lay dying, the ancient Maester begins to speak to Samwell Tarly of the Prince that Was Promised.
No one ever looked for a girl. It was a prince that was promised, not a princess. Rhaegar, I thought... What fools we were, who thought ourselves so wise! The error crept in from the translation. Dragons are neither male nor female, Barth saw the truth of that, but now one and now the other, as changeable as flame. The language misled us all for a thousand years. Daenerys is the one, born amidst salt and smoke. The dragons prove it.
Of course, the poor maester never makes it to Daenerys, but his words are enough to bolster the other clues that point to Daenerys as the long lost hero. She saw a comet on the day she was "reborn," came out of the fire untouched, and, of course, awoke her three dragons from stone.
This of course is assuming that the other fan favorite theory, that Jon Snow is Azor Ahai reborn, is untrue. We will probably not know the answer to this question until the series is almost completed. In the meantime, I'm most excited to find out what Sam plans to do with this information.