Daemon’s nightmares tie him to a much bigger Targaryen tradition

polygon.com:

As fire burns through the sky and the blood of dragons boils the smallfolk hundreds of feet beneath them, Daemon Targaryen (Matt Smith) finds himself haunted in Harrenhal. The run-down castle was identified as significant in the war due to its position in the Riverlands; Rhaenyra’s husband fled there to gain control over it — and escape his wife — and has been followed by a presence manifesting in his mind. He can’t walk the halls of the castle without visions of the past and, possibly, the future. Is Harrenhal haunted, or is Daemon?

After flying in upon Caraxes and finding no challenge to his being there, Daemon has found himself hallucinating. He sees visions of his late wife serving wine; of a younger Rhaenyra, sewing on the severed head of his nephew. The past is swirling in his mind, his attempt at escaping his pain by gaining space from Rhaenyra backfiring as his guilt follows him to Harrenhal. Considering what Daemon has presented to audiences since the series began, the most surprising thing about his new situation is that he’s able to feel guilt at all. With each episode’s passing, his nightmare fuses closer to his reality as his visions worsen.

Game of Thronesintroduced the Targaryens’ affinity with magic: Daenerys experienced a prophecy in the finale of season 2 while in the House of the Undying. She sees a vision of herself in the roofless throne room, ash covering the ground like snow. Knowing where that series went, the assumption can only be made that House of the Dragon’s visions for Daemon should be taken seriously. With these nightmares swarming his sight, he might consider working on fixing the past before his future is extinguished.

The Targaryen family is no stranger to magic — they ride dragons! A family believed to be of elevated status, it only makes sense that the Targaryens would have a stronger propensity toward believing in prophecies and giving heavier thought to hallucinations (and then probably calling them prophecies, as Viserys did