Matt Smith as Daemon Targaryen in "House of the Dragon" season two.Theo Whitman/HBOThere's a surprising cameo in "House of the Dragon" episode three.The episode sees Daemon Targaryen (Matt Smith) take control of the huge castle, Harrenhal.While there, he has a vision that leads to an unexpected appearance from a season one star.Warning, spoilers ahead for "House of the Dragon" season two, episode three.An unexpected "House of the Dragon" star just popped up for a cameo in the third episode of season two after previously saying they wouldn't come back.The episode sees Daemon Targaryen (Matt Smith) travel to Harrenhal, north of King's Landing in Westeros in an attempt to take it as a stronghold for the Blacks.But once he arrives, and the members of House Strong freely give it over to him, his first night is plagued by two things: A leaky roof to his bed-chamber, and a spooky vision about his life.In his dreamlike vision, Daemon believes that an unknown person tries to break into his room.