Emma D’Arcy and Olivia Cooke not only made waves on TikTok for their viral “Negroni Sbagliato” video, but also stunned onscreen as Princess Rhaenyra Targaryen and Alicent Hightower, respectively, in HBO’s Game of Thrones spinoff House of the Dragon this year. After a rigorous audition process, the two were cast as the adult versions of their characters (the younger roles are played by Milly Alcock and Emily Carey in the first three episodes), both of whom go through a tumultuous time struggling with complicated family dynamics, lost friendships and who is the true heir to the throne.

D’Arcy and Cooke spoke to THR about how they prepared for their roles, their most challenging scenes and decompressing after the show’s darkest moments.

How did you get attached to the project?

EMMA D’ARCY It was about three months of self-taping in my living room in the middle of the pandemic, so it was amazing. Actually, it felt like living on an island and trying to make cinema or something, because I didn’t see anyone or really do anything, but supposedly I was in conversation with one of the biggest TV shows in the world. My partner and I cobbled together a wig out of literally a bag of hair and then after three months of doing that, I was invited for a four- or five-hour in-person audition, did that, and then after that, I was told, “You’ll hear something next week.” And then I didn’t. Then I was told it was probably not going my way. And I thought, “Wow, it’s a real shame.” I went to the countryside, just for the weekend, to start metabolizing, and at the end of that weekend I had about 14 missed calls from my agent. I spoke to him the next morning to hear, “They changed their mind! Do you want to do it?” So weird, honestly. A very solitary process that went on seemingly half a year.

OLIVIA COOKE Similar to Emma, it was almost like it gave me a bit of a purpose in lockdown. It was like clocking in for work. I started off with a tape for Rhaenyra. And then they were like, “Can you have a look at these sides?” which were for Alicent. And then they went back to Rhaenyra and then to Alicent again, which was my final audition. Then, somewhere in between that, I had a meeting with [co-showrunners] Ryan [Condal] and Miguel [Sapochnik] about my tapes and how they saw Alicent. They were basically coaching me on how to get the job in my next tape, which was really, really lovely. And it felt good. But then they put me on hold for two weeks —

D’ARCY That’s exactly what happened to me! It’s insane! They call and they’re like, “We want you to play the part,” and you’re like, “That’s as good a sign as you’re going to get,” and then two months later you’re still fucking auditioning. It’s insane.

COOKE That was at the end of August where they were like, “We’re going to put you on hold. Don’t take any jobs.” I was like, “It’s the pandemic. I’m not going to get any jobs!” And then two weeks turned into six weeks and then, in the middle of October, I got a call from all my agents, which is usually a good sign that you’ve got the job.

How did you prepare for your roles?

COOKE We both went on a bit of a deep dive into Game of Thrones — because neither of us had seen it before — and read the book, read the scripts, chatted endlessly with Ryan and Miguel and [writer and executive producer] Sara Hess. And that was it, really. I didn’t really do much soul-searching or anything like that.

Emma, talk to me about learning High Valyrian.

D’ARCY My phrase book would need to be close at hand. But I can do the basics. I can order you a cappuccino or hail a cab or whatever. I really enjoyed that process. I was lucky because I had a big High Valyrian monologue, but I didn’t have lots of dialogue sections in it. It’s a fully operational language, so I think it’s really satisfying to unpick the thing. We get sent the English translation, the High Valyrian, a phonetic translation, and then also audio recordings, and one [method] would be to try and parrot back the audio recordings. It’s ideal as an actor to be able to command the language you’re having to use. I had a really nice time using gestures, for example, to embed meaning into unfamiliar language. And now I have an incredible rolling R. So really, it’s paid back dividends.

Olivia, you play someone who is caught between two worlds, especially in episode eight when your son Aegon is accused of rape by his servant Dyana. What was your preparation like for that scene?

COOKE Sara Hess wrote that episode, so I spoke endlessly with her and [director] Geeta Patel. It’s such a gross situation that Alicent has to be in because, if she really is propping up her son to be the heir to the throne, to believe this woman and to out him, the whole dynasty would come crumbling down. You have to in that moment think about what Alicent herself truly stands for, and that’s for her children and for order. Her first thought is to love and protect her son as much as possible, which is so fucking grim. But at the same time, her humanity gets the better of her and she can’t help but really feel for this girl — but then an iron shield has to come in. There’s a task at hand, and that’s to, one, reprimand Aegon, but also to quiet anyone who knows. It was just such a grim scene to film, and it was an eerie, quiet, subdued atmosphere on set that day.

Did you ever feel you needed to decompress after scenes?

COOKE We were just talking about this. A lot of the show’s [filmed] in Watford, which is quite far away from where we live in London. Next season, we’re saying we need to find a local pub in Watford, where we can go and just have a drink and just be like, “What the fuck did we just do?”

D’ARCY It’s true, because it’s one of the weird quirks of shooting. You can feel it in your body sometimes, after 15-hour workdays, that you need to unravel. You’ve got a banging headache, but because you so often commute at the end of the day, and the hours are so long, it gets to the end, and people have vanished within about two minutes. A lot of that decompression time happens alone.

COOKE You see all the Targaryens just fucking Frisbee their wigs and then get back into the car.

What was your most challeng­ing scene?

D’ARCY One of them was the birth scene in episode 10. That was challenging for a number of reasons: One of them is just a practical concern, which is that the character has already done a birth in the series, and you’re trying to find differentiation between these things. You’d always want to understand the conditions of an event like that really intimately. In terms of performance, there’s a slightly unique challenge if you’re doing two big birth scenes in five episodes. Simultaneously, this is no straightforward delivery; the child is delivered stillborn. That event really marks the collision of two historic fears for Rhaenyra. On the one hand, she has this long-standing concern that’s about the possible incapacitation that can come with being forced to bear children, and the threat of mortality. She lost her mother in childbirth as a child. She spends years waiting to be called up, essentially, for the news to arrive that her father has died. And that now the throne is yours, and it’s time for your ascension. The two things happen concurrently. The whole episode’s a nightmare. Because there’s not just one mountainous event in the episode. It’s like the Alps.

I think in that birth scene, my feeling was that for a character who has had such a complex relationship with how her gender allows her to relate to the world, it’s like she’s suddenly given a choice to be a king or to be a mother and maybe neither, or maybe both. Trying to tell a narrative throughline while also doing something that’s physically demanding … it’s just challenging, and you don’t know if it comes off, really, until you see it onscreen.

COOKE In episode eight, the scene with Dyana where she tells me that my son raped her … and then also, I had to hit Tom [Glynn-Carney] really hard in the scene. And Tom, being Tom, was like, “No, just hit me.” The first go-around, I clipped him on his chin. And he was like, “No, just really wall at me,” and I just really fucking went for it to the point where it echoed all the way through the hall, and my hand suddenly had a heartbeat. Luckily the camera’s on Tom, and I was completely taken out of the scene [because I was] trying to suppress a really awkward laugh. God knows what it did to his face. … We only did it once or maybe twice. But it was like, “Oh my God, don’t mess with you.”

Interview edited for length and clarity.

This story first appeared in a December stand-alone issue of The Hollywood Reporter magazine. To receive the magazine, click here to subscribe.