In the lore of Game of Thrones, the ruined castle, Harrenhal, has a reputation for being haunted. Prince Daemon Targaryen (Matt Smith) discovered that there may be some truth to those rumors in House of the Dragon Season 2 Episode 3. But the vision that Daemon saw there may be only the beginning for one of the show's original cast members who unexpectedly returned to the series.

Warning: the following contains spoilers from House of the Dragon Season 2 episode 3. If you haven't seen the episode or don't want to know what's in it, stop reading now.

Near the end of the episode, Daemon is drawn out of his room at Harrenhal before he encounters his estranged wife, Rhaenyra, reattaching the head of the murdered prince, Jaehaerys Targaryen. But instead of Emma D'Arcy's adult Rhaenyra, Daemon sees her younger self as portrayed by former cast member Milly Alcock, who was recently cast as the next Supergirl.