Milly Alcock.

Milly Alcock plays a young princess Rhaenyra Targaryen on HBO’s Game of Thrones prequel series, but she has no idea how the season ends. Not because her character suffers a Ned Stark–like demise in House of the Dragon’s early episodes, but because the 22-year-old Australian actress is replaced by Emma D’Arcy when the series jumps ahead ten years. “We didn’t work together at all!” Alcock said. “Emma and I wanted to meet each other, but it was very clear early on that it was a choice HBO made.” Alcock hasn’t seen the scripts for D’Arcy’s part of the series, and when she spoke with Vulture over Zoom, she’d only been sent screeners for the episodes she’s in. She jokes she may just start watching once the show gets to D’Arcy, since “I know what happens before then.”

What does happen, as we see in the series premiere, is a whole lot of scheming about who will assume the Iron Throne. Rhaenyra, the only surviving child of king Viserys Targaryen (Paddy Considine), is his chosen heir, but she’s a woman, and Viserys’s younger brother prince Daemon (Matt Smith), believes it should be his. When we meet Rhaenyra as a young teen, her closest ally is Alicent Hightower (Emily Carey), the teenage daughter of the Hand of the King, but political machinations might just pull them apart, too.

So, Rhaenyra enters the show riding a dragon. What’s that like to film?
It’s incredibly mundane. It’s very underwhelming. You don’t really learn, they just throw you onto a machine that’s basically like a bucking bronco. You’re elevated ten meters in the air, all harnessed in. We worked on the Volume stage [filming technology used on The Mandalorian where actors film in front of a screen with a render of the final background] for exterior stuff, so that was helpful as a visual aid. You can see the sky on the LED screens. There’s a bunch of guys with leaf blowers, and they just blow it in your face. I found it very difficult, though. I didn’t know what to do with my face. They were like, “Can you look more angry?” And I was like, “What do you mean?”

How familiar were you with Game of Thrones before doing this?
I was completely oblivious. I was about 10 when it came out, and it wasn’t really age appropriate, you know what I mean? Fantasy isn’t my go-to genre. But I watched it over pre-production and fell in love with it, and understood why it had the amount of success that it did. It’s very good!

As Rhaenyra, you have to adopt a very stiff, formal accent and gestures and posture, especially in the scenes in court. How did you think about her mannerisms?
The costumes did a lot of that for you. They affect your breathing because they’re so restricting, so that in turn affects how you speak and sound. The first episode is a lot of the stuff that we did in the first couple weeks of shooting, and I can see that I’m not in her body as much as I was further along in the process. I’ve never played someone who had that kind of status and gravitas. I watched a lot of films; my biggest reference was Cate Blanchett in Elizabeth: The Golden Age.

Oh, I love her going, “I, too, can command the wind, sir!” in that.
God, it’s so good. You’re just like, chills. And all the interesting relationships in that film, and Cate’s voice and the way she uses her power, and when she doesn’t — I was like, that’s Rhaenyra!

There’s a scene in the first episode where Rhaenyra and Alicent are alone in the Godswood, and you get a sense of their closeness as young girls. How did you and Emily Carey approach their dynamic?
It’s funny, because it reflects a lot of me and Emily’s relationship. We’re two young women who felt completely out of our depth in a very niche and specific circumstance. We didn’t really have anybody that could relate to us or understand us. That is, essentially Rhaenyra and Alicent’s relationship. These two young women have been thrown into this world of men and they’ve got all these expectations thrust upon them. They have extreme privilege, but they can’t actually do what they want to do. The demise of their friendship is because of choices made by men.

What did you bond over initially?
Well, first it was just like, “Holy shit, what the fuck is going on?” Em’s more experienced than I am, so we were just like, This is absolutely crazy. And we can’t tell anyone!

It must be very strange psychologically to know you’re going into this closely scrutinized show and you can’t tell anyone.
I’m still processing it. It’s mental, because an experience that was so intimate and so ours on set is now everybody else’s. Especially in a franchise where there’s already an established audience, we have to come to them. They don’t come to us. It’s every emotion under the sun, really.

How did you learn your dialogue when you speak High Valyrian?
I obviously didn’t learn the whole language. I did not do High Valyrian Duolingo. I would learn the scene in English so I knew what was going on, and then I would get it printed out in High Valyrian to learn phonetically. Then I listened to a recording of the guy who made the language speaking it. Then it became muscle memory and I didn’t have to think about what I was saying. The melody of High Valyrian was actually nice to play with, because you could fall into it and not think about what you were saying. Then, I would try to think about what I was saying in English as I was speaking another language. But it was fun! I had fun with Matt! He was great!

What was it like working with Matt? You have a lot of charged scenes together.
Matt is an incredible actor, and an incredible role model for a lot of the young cast, especially in terms of set etiquette and knowing when to speak up and when to not speak up when it isn’t your responsibility or lane. Our dynamic is so interesting onscreen, and it was so much fun to spend time with him and really work on it. It’s funny, because he’s so not like that character. He’s really lovely.

Then there’s Fabien Frankel’s Ser Criston Cole, who offers a bit of an escape from the palace for Rhaenyra.
I mean, I just loved Fabs. We’ve become very good friends on this job. He was the first person I met in real life on this show. We asked to meet each other through our agents, and we went on a massive walk and got really drunk together. I wish I had more scenes with him because I think that dynamic is so poignant in terms of her perspective on the royal family and her role within it.

There are a few scenes in the first few episodes where they get to go off together that are lovely.
Wait, have you seen that far in? I haven’t seen them yet! That was so much fun. Riding that horse was so much fun. Horse riding is so much more fun than riding a dragon.

So horse riding fun, dragon riding not?
Oh yeah, because you’re there, on a horse, charging around, on the set. I was very proud of my horse-riding abilities.

You can put it on the special-skills section of your résumé. 
I actually know how to do it now. I’m not lying!

Milly Alcock Says Riding a Horse Is More Fun than a Dragon