I haven't seen it yet, will stream in a little bit.
I just watched the
"The Lord of Light" segment in the Histories & Lore extras for the third season, and it is narrated by Paul Kaye as Thoros of Myr. This part of it stood out to me:
"Man once again faces the war for the dawn, which has been waged since time began. On one side is the Lord of Light - the Heart of Fire, the God of Flame and Shadow. Against him stands the Great Other, whose name may not be spoken - the Lord of Darkness, the Soul of Ice, the God of Night and Terror. According to prophecy, our champion will be reborn to wake dragons from stone and reforge the great sword Lightbringer that defeated the darkness those thousands of years ago. If the old tales are true, a terrible weapon forged with the lifeblood of a loving wife's heart. Part of me thinks man was well rid of it, but great power requires great sacrifice. That much, at least, the Lord of Light is clear on."
This is derived from the books wherein Melisandre stated:
"When the red star bleeds and the darkness gathers, Azor Ahai shall be born again amidst smoke and salt to wake dragons out of stone. The bleeding star has come and gone, and Dragonstone is the place of smoke and salt."
The bit about waking dragons from stone must pertain to Daenerys as her dragon eggs were petrified, but it hasn't been mentioned in the show, nor the name "Azor Ahai", only:
And:
"After the long summer, darkness will fall heavy on the world. The stars will bleed. The cold breath of winter will freeze the seas and the dead shall rise in the North. In the ancient books, it's written that a warrior will draw a burning sword from the fire. And that sword shall be Lightbringer."
[s02e01 "The North Remembers"]
Stannis Baratheon then enacted a ritual to ostensibly "fulfill" the Lightbringer portion of the prophecy:
Mel was obviously mistaken about Stannis, and now believes that Jon Snow is the Prince Who Was Promised because the Lord of Light granted his resurrection. Two of his staredowns with the Night King
-who may sense his deeper identity- have also made me believe that Jon might be The One.
The red comet as the prophesied "bleeding star" was seen at the beginning of season 2 right after the birth of the dragons. Daenerys was, in a sense, born again out of Drogo's funeral pyre from its "smoke" and the "salt" (of her sweat?), or alternatively, this part pertains to her actual birthplace of Dragonstone which has salt from the sea and smoke from an active volcano there, the Dragonmont. The show has really pointed to Daenerys being the One foretold, as with this scene in Mereen:
KINVARA (High Priestess of R'hllor from Volantis):
"Daenerys Stormborn is the one who was promised. From the fire she was reborn to remake the world. Her dragons are fire made flesh, a gift from the Lord of Light. Daenerys has been sent to lead the people against the darkness in this war and in the great war still to come." [s06e05 "The Door"]
And on Dragonstone:
MELISANDRE:
"The prince who was promised will bring the dawn."
DAENERYS:
"I'm afraid I'm not a prince."
MISSANDEI:
"Your Grace, forgive me, but your translation is not quite accurate. That noun has no gender in High Valyrian, so the proper translation for that prophecy would be, 'The prince or princess who was promised will bring the dawn'."
MELISANDRE:
"I believe you have a role to play. As does another the King in the North, Jon Snow."
[s07e02 "Stormborn"]
An important and intentional qualification is made here (which parallels same by Aemon Targaryen in the books) which allows Danaerys to fit the prophecy. And when Jon Snow arrived:
MELISANDRE: (to Varys):
"I've done my part. I've brought ice and fire together." s07e03 "The Queen's Justice"
She then told Varys that she is leaving for Volantis but will return --which is in line with her prophecy given to Arya back in Season 3 that they would meet again.
Melisandre will share her knowledge about Jon Snow and his resurrection with Kinvara in Volantis who is perhaps more accurately attuned to the Lord of Light than she is (considering how incredibly wrong Mel was about Stannis, and how insightfully correct Kinvara was about the details of Varys' past). And because The Great War from their religious beliefs is now upon the world, they will return to Westeros with a small army of red warrior priests bearing flaming weapons, a blessing from the Lord of Light (in the show anyway):
They may also inform Jon and Daenerys of what is required to defeat the Night King. And/or this knowledge will be conveyed via the old books that Sam stole from the Citadel or by Bran/3ER who can actually visit the remote past to show us Azor Ahai and how he defeated the Darkness.
As Thoros related above, to make Lightbringer, the "Red Sword of Heroes", Azor Ahai sacrificed his beloved wife, Nissa Nissa, by stabbing her through the heart so that her spirit could enter the sword and make it potent. This weapon must be the bane of the Night King...though why it didn't destroy him for good when Darkness was defeated last time is a mystery.
The reincarnated prince is said to have "a song", the song of ice and fire. Jon and Daenerys BOTH seem to have roles for fulfilling the prophecy, the two may be the reincarnations of both Azor Ahai
and Nissa Nissa, and if this is supposed to replay as it did in the ancient past, then one will have to sacrifice the other in order to create Lightbringer. Jon is the sword-wielding warrior of the two, but maybe this will be flipped around in a new way?