House of the Dragon, the Game of Thrones prequel is going to be based on House Targaryen, who is currently making casting calls for its lead characters. The casting calls have gone out. The show will be based on George R.R. Martin's Westeros companion book Fire & Blood. It will take place about 300 years before the Game of Throne's action, and we will get to see the beginning of the Targaryen House. The House of the Dragon is still in the works, and we do not have any clear release date details about it. But Martin's story of the Targaryens is finally happening, into a series, with the help of Ryan Condal and director Miguel Sapochnik, who also worked on Game of Thrones. Sapochnik is the one who made all those spectacular episodes, "Battle of the Bastards" and "Hardhome" are just the tip of the iceberg. Game of Thrones Spinoff Started The Casting Calls According to some reports, people know more about the official casting calls for the new series, which means that some of us know a bit more about what we should expect from the series. Aegon, Visenya, and Rhaenys Targaryen are the leads, which means that the series will show the story of the Targaryen invasion of Westeros and their rise to power. Aegon Targaryen is a Caucasian male, and he married his two sisters, Raheny's and Visenya. He is quiet and pious and also ruthless. He is riding the Balerion dragon. Visenya Targaryen is a Caucasian female. She is the older sister and the wife of Aegon Targaryen. She is very serious and unforgiving. She is riding the Vhagar dragon. Rhaenys Targaryen is a Caucasian female. She is the younger sister and the wife of Aegon Targaryen. She is graceful, kindhearted, but also impulsive. She is riding the Meraxes dragon.