Joe Otterson TV ReporterThe “Game of Thrones” prequel series “House of the Dragon” at HBO has found its first cast member — English actor Paddy Considine.Variety has learned that Considine has signed on to star in the series in the role of King Viserys I, who chosen by the lords of Westeros to succeed the Old King, Jaehaerys Targaryen, at the Great Council at Harrenhal. A warm, kind, and decent man, Viserys only wishes to carry forward his grandfather’s legacy.