One of the most intriguing early reveals from House of the Dragon’s trailers was the return of Game of Thrones’ Valyrian steel dagger. The catspaw dagger was used in Game of Thrones season 1 to try to murder Bran Stark, then returned in season 7 when Bran gave it to Arya. The ancient knife then had an integral role in Game of Thrones season 8’s Battle of Winterfell, as Arya Stark used it to kill the Night King and destroy the White Walkers. House of the Dragon now gives more clues to the Valyrian steel dagger’s origins and its deeper connection to Aegon’s prophecy and the Night King.
Viserys Targaryen notably carries the catspaw dagger everywhere he goes, with the King finally showing Rhaenyra the inscription on the steel in House of the Dragon episode 4’s ending. Viserys reveals that he is unsure of the true origin of the blade, but knows that it was once owned by Aenar Targaryen, who brought the family to Dragonstone before the Doom of Valyria. The dagger was then passed onto Aegon the Conqueror, who had his Song of Ice and Fire dream etched into the steel by a pyromancer. Written in High Valyrian, the inscription reads “From my blood come the Prince That Was Promised, and his will be the song of ice and fire.”
The words on the dagger now tie Aegon’s dream to the Prince That Was Promised prophecy, which was what motivated Melisandre throughout Game of Thrones. The Red Woman’s prophecy claimed that the Prince That Was Promised was a savior in the religion of the Lord of Light who would pull Lightbringer from the flames and bring an end to the darkness. This meant that the prophesied Prince would save humanity from complete annihilation by the Night King and White Walkers, which is exactly what Aegon sees in his vision. However, Aegon’s dream before House of the Dragon adds another layer by revealing what Melisandre wasn’t exactly aware of: The Prince would be a descendant of House Targaryen who would sit on the Iron Throne and unite Westeros against the cold and dark. The prophecies now essentially being one and the same indicates that the envisioned Prince That Was Promised is both Daenerys Targaryen and Jon Snow.