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  ===Casting===
  Jim Broadbent joins the series as Archmaester Ebrose
  "Dragonstone" saw the introduction of Jim Broadbent as Archmaester Ebrose at the Citadel. His casting in the series was initially announced by HBO to ''Entertainment Weekly'' in August 2016, and at the time was only revealed as a "significant" role in the seventh season. In a subsequent interview, Broadbent revealed his role in the series, and that he would be sharing his scenes with John Bradley, who portrays Samwell Tarly.
  Prior to the episode airing, it was announced that musician Ed Sheeran would be making a cameo appearance at some point during the season. According to David Benioff, they had been trying for years to get him onto the show as a surprise for Maisie Williams, who portrays Arya Stark in the series and is a fan of Sheeran. Before the episode's official release, Sheeran stated about his appearance that "Nothing exciting happens in this scene, we just have a conversation and that's kind of it." In "Dragonstone", Sheeran portrays a Lannister soldier, who Arya happens upon when she hears him singing a song that is unfamiliar to her. The song originates from George R. R. Martin's ''A Song of Ice and Fire'' book series, which the television series is adapted from, and is titled "Hands of Gold". In the book series, it is sung by a character known as Symon Silver Tongue, a character unrelated to Sheeran's portrayal.