"House of the Dragon" actress Gayle Rankin, who plays the Witch Queen of Harrenhal, Alys Rivers, has voiced frustration that the show has yet to introduce Mushroom, a notorious jester character from George R.R. Martin's source material "Fire and Blood". The remark, made in an interview promoting the show's third season, highlights how closely Rankin has studied Martin's book and reflects wider fan curiosity about which characters from the dense historical text will make it onto screen before the series concludes.

Mushroom is a crude court jester in Martin's book whose fictional tell-all memoir underpins much of what readers know about the "Dance of the Dragons" civil war, but he has not appeared in the HBO adaptation. With only one season of the show remaining, Rankin said time is running out for the character to be included, and she called on showrunner Ryan Condal to make it happen. The interview otherwise focused on Rankin's evolving portrayal of Alys Rivers, including fan reception and her character's romantic entanglement with Aemond Targaryen in season three.