The Game of Thrones prequel series House of the Dragon announced more cast members on Tuesday, and by extension revealed a bit more about the show itself. According to HBO, actress Milly Alcock will play "Young Princess Rhaenyra Targaryen" while actress Emily Carey will play "Young Alicent Hightower." This means that they will play younger versions of the characters played by Emma D'Arcy and Olivia Cooke, respectively.
House of the Dragon is set about 180 years before the events of Game of Thrones, at a time when House Targaryen firmly ruled all of Westeros with a dozen fully-grown dragons at its command. Alcock is the latest addition to the dynasty, and presumably, Carey's character will not be far behind. The casting of "young" versions of these two characters tells us quite a bit about the timeline and format of the show based on George R.R. Martin's latest book, Fire and Blood — available here in print, digital and audiobook formats.
Alcock comes from Sydney, Australia, and is best known for starring in a TV show called Upright there. According to an interview with Vogue, she is 20 years old, and is also known for roles in Furlough, Reckoning and Pine Gap, among others. Meanwhile, Carey is best known for playing a young version of Diana in Wonder Woman, and a young version of Lara Croft in 2018's Tomb Raider revival.
HBO published character descriptions for their new role that are similar, but not identical to the descriptions of their older counterparts. This highlights the fact that Alcock and Carey's performance will be set earlier, telling us a different part of the story of the Targaryen civil war known as "The Dance of the Dragons."
House of the Dragon is based on Martin's 2018 book Fire and Blood, which is written as a Westerosi history book rather than a traditional novel. This allowed Martin to tell many stories and cover about 130 years' worth of chronology in very little time, and most importantly it means that the TV show will be based on a finished work rather than an ongoing series.
However, that also means the showrunners will have a lot more work to do in adapting the story and fleshing it out in a new format. From its broad historical context, the book Fire and Blood sometimes depicts a character over the course of many decades, including Princess Rhaenys and Lady Alicent. The addition of younger actresses for these roles tells us that many of those earlier scenes will be shown in the TV show.
This could mean we'll see flashback sequences, or perhaps tandem timelines in House of the Dragon. It will certainly help deepen the enmity between Rhaenys and Alicent as the war for the Iron Throne heats up. House of the Dragon is filming now and is expected to premiere on HBO sometime in the spring of 2022. Game of Thrones is streaming now on HBO Max.