According to Entertainment Weekly, HBO has begun the casting process for Game of Thrones prequel, House of the Dragon. The prequel was announced by HBO in October last year. Based on George R.R. Martin’s Fire & Blood, the prequel is set 300 years before the events of Game of Thrones. The book covers 100 years of Targaryen history and explores the stories of many Targaryen leaders. The show is expected to include Dance of Dragons, which is a civil war between the Targaryens. In terms of story, the show will be based on Martin’s novel Fire & Blood, which covered the history of the Targaryens, one of the great houses of Westeros, from around 300 years before the events of A Game Of Thrones. The events of the novel span around 150 years of history, however, so how the show will handle the timeline and which parts it will choose to emphasize remains a mystery. Likely candidates for featured characters include historical heavy-hitters like Aegon The Elder, the first King Viserys (not to be confused for Danny’s horrible brother, who inherited the name), and Rhaenyra Targaryen, his daughter. It’s probably a safe bet to assume there will be plenty of dragons, though, so at least there’s that. Details about the characters of House of the Dragon are under the wraps. The show may focus on Aegon Targaryen and his conquest to become the leader of House Targaryen, which is something frequently referenced in Game of Thrones. Ryan Condal will be serving as the showrunner alongside Miguel Sapochnik. Sapochnik will also direct some episodes of the show. House of the Dragon is slated to debut in 2022.