NEW YORK – They anchored half the season of one of the biggest shows on television, but Milly Alcock and Emily Carey have no idea what they are doing next – including whether they will ever return to the Game Of Thrones prequel, House Of The Dragon, in flashbacks or otherwise.

The stars are at loose ends after playing two of the primary characters in the hit HBO fantasy series, which has been averaging 29 million viewers an episode: Princess Rhaenyra Targaryen (Alcock), heir to the Iron Throne of Westeros, and Queen Alicent Hightower (Carey), who hopes her offspring will one day usurp the claim of her one-time best friend.

The fifth episode, which aired recently, was the end of their tenure. A narrative time jump will see English actresses Emma D’Arcy, 30, and Olivia Cooke, 28, take over as Rhaenyra and Alicent respectively.

For Alcock and Carey, it is a time of uncertainty.

“Me and Emily had this conversation today,” Alcock, 22, an Australian, said during a conference call from London last week. “We were like, ‘I don’t know what the **** I’m doing any of the time now.’ I’ve been pacing.”

English actress Carey, 19, said: “Milly paces, and I sit and do Lego, and that’s the vibe.”

Like the characters they portray, the two have been asked to shoulder an enormous burden at a young age.

They have been crucial components in the big-budget gamble that has paid dividends, and Alcock’s and Carey’s skills in depicting their characters’ complex relationship have been a key to the show’s success.

Q: The two of you anchored the first five episodes of the spin-off of the biggest show in HBO history, which has become a huge hit in its own right. How have your lives changed?

Alcock: There’s been a great sense of terror, fear, excitement. But there’s also been this utterly welcoming reassurance that me and Em have the privilege of being able to do this for the rest of our lives. That’s something that any actor dreams of – having a sense that it’s not all going to fall apart underneath you.

Carey: It’s strange, being visible. For me, that’s the main thing that’s changed – going from being able to blend in, to being seen.

Q: On a fundamental level, this story hinges on Rhaenyra and Alicent. How was their relationship reflected in the relationship between the two of you as actors?

Carey: We’re very lucky in that we get along in real life, so the chemistry came very organically. We’re quite like our characters. I’m very Type A, very anxious and very dutiful. I follow the rules. Mil’s a lot more like Rhaenyra in that sense. But I see Milly as a big sister, which is different when the characters are on-screen. Still, that closeness you see between Rhaenyra and Alicent is definitely a reflection of ours in real life.

Alcock: Me and Em went through a very similar experience that our characters went through. We were both thrown into this massive role and when it actually happened, you don’t know how to react. We’re two young women who haven’t done massive projects before, in an environment full of men. We were forced to hang on to each other for dear life.

Carey: And we haven’t let go yet.

Q: One of the show’s central themes, about women’s autonomy over their own bodies and futures, has become even more salient since production began, with the United States Supreme Court overturning Roe V Wade.

Carey: I think that’s what makes the show so watchable, relatable to a modern-day audience. It’s so much more than fantasy and dragons. There’s grounded, truthful topics and storylines that reflect the world we live in.

Alcock: It explores the trauma that these two women would have faced within that world – not only the patriarchy, but the internalised misogyny. These two women are forced to battle with each other because of the choices made by men. The irony of social media being like, “I don’t want to say goodbye to Milly for Emma”, or comparing (Emily to Olivia). That is what the whole show is about and people are still doing it. So it’s clever.

Q: You must be curious to see how the characters will continue without you.

Carey: Yeah, I’m so intrigued. We didn’t read the scripts that we weren’t in, so we know very little about what happens after we leave.

Alcock: We weren’t given (the scripts). I’ve asked for them so much and they were like, “No, you cannot.” I’m going to be watching on the edge of my seat because I want to know what’s going to happen.

Q: What does it feel like to hand over the reins of your characters to new actors?

Alcock: I’m so excited to see what Emma did with Rhaenyra. There’s no way I could have played her in the later stages of her life because I don’t have the same lived experience that Emma has. So I’m so keen.

Carey: That’s so true. When people say, “Do you wish you could do the rest of it?”, I’m always like, “I don’t know.” I don’t think I have the capacity.

But I will be honest: It’s strange handing off a character that is so personal. As actors, we put so much of ourselves into the people we play. So it’s strange having to leave someone’s story halfway through.

At the same time, it doesn’t feel unfinished because it’s going into obviously amazing hands with Olivia. It’s going to be really cool – and weird – to watch the show as a viewer and not be critiquing our own performances, and just take it in and appreciate the show for what it is. NYTIMES

• House Of The Dragon airs on HBO GO with new episodes every Monday at 9am.