The addition of two new younger cast members to the "Game of Thrones" prequel, "House of the Dragon," suggests flashback scenes will play out in the series.

The new cast additions in the HBO show include Milly Alcock and Emily Carey. They will play younger versions of Princess Rhaenyra Targaryen and Alicent Hightower, respectively. The 19-year-old Australian Alcock ("The Gloaming," "Reckoning") plays the role of "the king's firstborn child" who is of "pure Valyrian blood." She is also a dragonrider.

"Many would say that Rhaenyra was born with everything... but she was not born a man," reads the character description from The Hollywood Reporter.

Meanwhile, 18-year-old British actress Carey, whose other credits include "Casualty" and "The Lost Girls," to name a few, plays the daughter of Otto Hightower, the Hand of the King in "House of the Dragon." She is described as "the most comely woman in the Seven Kingdoms." She grew up in the Red Keep, "close to the king and his innermost circle and she possesses both a courtly grace and keen political acumen."

Emma D'Arcy ("Truth Seekers," "Wunderlust") plays the older version of Princess Rhaenyra and Olivia Cooke ("Bates Motel") is the elder version of Alicent Hightower.

Both Carey and Alcock have since reacted to news of their casting in the "Game of Thrones" prequel "House of the Dragon." On her Instagram Live on Tuesday, Carey admitted that she read for her role and remembered it being a "fairly long audition process." She said she "didn't know what the project was or the character was until" she got in.

"I can't answer any questions or who I'll be in scenes with but stay tuned for more and I love you and have a great Tuesday!," she said.

Carey also posted a screenshot of the casting news from The Hollywood Reporter and captioned it, "the dragons out of the bag." Meanwhile, Alcock shared the same screenshot on her Instagram and wrote, "....Ahhh," to which Carey commented, "DUDE."

Aside from Carey, Alcock, D'Arcy, and Cooke, other cast members in the "Game of Thrones" prequel "House of the Dragon" include Paddy Considine as King Viserys Targaryen, Matt Smith as Prince Daemon Targaryen, and Eve Best as Princess Rhaenys Velaryon. Fabien Frankel is also cast as Ser Criston Cole, Sonoya Mizuno as Mysaria, Rhys Ifans as Otto Hightower, and Steve Toussaint as Lord Corlys Velaryon.

"Game of Thrones" prequel
Emily Carey and Milly Alcock join the cast of HBO's "Game of Thrones" prequel "House of the Dragon." House of the Dagon/HBO