Viserys told Rhaenyra about the Targaryen prophecy called the Song of Ice and Fire : a coming threat from the far North that would bring darkness and destroy the world of the living unless the realm was united to face it.

What he meant

  • The prophecy traces back to Aegon the Conqueror’s dream.
  • It says a terrible winter would come from the North.
  • Viserys believed the prophecy meant a Targaryen ruler would help save the realm.
  • He passed that secret to Rhaenyra as the heir and future protector of Westeros.

Why it matters

That prophecy becomes a major part of the show’s larger Game of Thrones connection, and it also fuels the confusion around Viserys’s final words to Alicent later on.

TL;DR: Viserys told Rhaenyra that the Targaryens carry an ancient warning about a deadly darkness from the North, and that their line has a role in stopping it.