House of the Dragon: Aegon Targaryen's White Walker prophecy and Daenerys Targaryen references explained

“Aegon called his dream the Song of Ice and Fire,” King Viserys (Paddy Considine) tells his daughter Princess Rhaenyra (Milly Alcock) in the first episode of House of the Dragon.

The Game of Thrones prequel show was unleashed on the world on Sunday (August 21), and it features a number of tributes to its predecessor.

‘Heir of the Dragon’, as the episode is titled, opens with text explaining the story takes place 172 years before Daenerys Targaryen (Emilia Clarke). And fans rejoiced when Rhaenyra uttered the line made famous by her descendant: “Dracarys!”

But there was a crucial scene towards the end of the episode which has everyone talking about the existential threat which loomed in Game of Thrones: the White Walkers.

In front of the skull of legendary dragon Balerion the Black Dread, King Viserys I tells his daughter: “Our histories, they tell us Aegon looked across the Blackwater from Dragonstone, saw a rich land ripe for the capture.

"But ambition alone is not what drove him to conquest. It was a dream. And, just as Daenys foresaw the end of Valyria, Aegon foresaw the end of the world of men.

"It is to begin with a terrible winter, gusting out of the distant north. Aegon saw absolute darkness riding on those winds, and whatever dwells within will destroy the world of the living.

"When this great winter comes, Rhaenyra, all of Westeros must stand against it. And, if the world of men is to survive, a Targaryen must be seated on the Iron Throne.

House of the Dragon has some major references to Game of Thrones, including Daenerys Targaryen and the Long Night (HBO)

"A king or queen strong enough to unite the world against the cold and the dark.”

Here’s what King Viserys’ revelation means for the world of House of the Dragon and Game of Thrones.

Who is Aegon I the Conqueror? How did he conquer Westeros?

Aegon I was the first king to unite Westeros into the Seven Kingdoms, and built the Iron Throne from the swords of his defeated enemies.

Viserys Targaryen (Paddy Considine) tells Rhaenyra Targaryen (Milly Alcock) about Aegon's dream in House of the Dragon

He conquered the lands with his sister-wives Visenya and Rhaenys, riding their dragons Vhagar, Meraxes, and Balerion the Black Dread.

Before him, the Targaryen family lived on Dragonstone, a large island to the east of Westeros. They had fled from the ancient Valyria in Essos after Daenys Targaryen had a prophetic dream of the city's doom – which came true.

This is who King Viserys is referring to when he talks about Daenys foreseeing the end of Valyria.

Born on Dragonstone, Aegon began exploring Westeros. He flew his dragon Balerion above the lands and had a table made into a map of Westeros. This can be seen in Game of Thrones, when Stannis Baratheon and later Daenerys Targaryen occupy Dragonstone.

The Night King riding Daenerys' undead dragon Viserion in Game of Thrones (HBO)

But in House of the Dragon King Viserys – who is the fifth Targaryen king to sit on the Iron Throne – says it was not just ambition that drove Aegon to take over Westeros, but an apocalyptic vision like what Daenys saw.

“Aegon called his dream the song of ice and fire,” Viserys tells Rhaenyra, using the name given to the series of George R.R. Martin books Game of Thrones is based on.

He says: “This secret has been passed from king to heir since Aegon’s time. Now you must promise to carry it, and protect it. Promise me.”

What was Aegon I’s vision? White Walkers and the Long Night

This prophecy is almost definitely a reference to the White Walkers, an impending threat introduced in the very first scene of Game of Thrones.

Daenerys Targaryen (Emilia Clarke) and Jon Snow (Kit Harrington) in Game of Thrones (HBO)

We learn in the previous show that White Walkers were made by the Old Gods, the Children of the Forest, to fight the First Men who invaded Westeros thousands of years ago.

Able to reanimate the dead as hoardes of wights, the White Walkers grew incredibly powerful and threatened to wipe out all life. A winter descended on the world, known as the Long Night, which was said to last an entire generation.

No longer able to control the White Walkers, the Children made a pact with the First Men to fight them together. They managed to defeat them in a conflict called the Battle for the Dawn, and cast them north into the Lands of Always Winter.

The Wall, an enormous ice structure with magical protections, was built to protect Westeros from the White Walkers’ return. The Night’s Watch, which Jon Snow becomes part of in Game of Thrones, was set up to guard the wall from such a threat.

What happened to the White Walkers in Game of Thrones?

Warning, spoilers for the ending of Game of Thrones.

In Game of Thrones, the threat of the White Walkers gradually builds throughout the eight seasons. But it isn’t until the last moments of Season 7 when the army of the dead marches on Westeros.

Its leader, the Night King, kills one of Daenerys Targaryen’s dragons and uses its reanimated body to burn through the Wall.

Season 8 Episode 3 ‘The Long Night’ shows the epic battle between the living and the dead at Winterfell, where Daenerys Targaryen and Jon Snow join forces to fight the hoards of Wights.

Arya Stark uses assassin skills she had learned from the Faceless Men to kill the Night King with a Valyrian steel blade – killing every White Walker and wight in the process.

It is that very blade which King Viserys hands his daughter Rhaenyra Targaryen in House of the Dragon when he names her as his heir.

What does Aegon’s dream mean? How does it relate to Game of Thrones

The revelation in this House of the Dragon episode suggests Aegon Targaryen knew about the White Walkers, and that was why he conquered Westeros in the first place.

And fans are pointing to the alliance of Jon Snow and Daenerys Targaryen as evidence Aegon Targaryen’s dream to save Westeros came true.

Perhaps both Jon and Daenerys are the king and queen referred to with Viserys’ words: "If the world of men is to survive, a Targaryen must be seated on the Iron Throne. A king or queen strong enough to unite the world against the cold and the dark.”