The penultimate episode of Game of Thrones Season 7 was arguably the most stressful installment since the Red Wedding — North of the Wall, we saw one of Daenerys' beloved dragons die, before being resurrected by the Night King, while back in Winterfell, Arya and Sansa escalated their cold war to nuclear levels, all thanks to Littlefinger's puppeteering.

With only one episode left this season — and only six episodes to come in Season 8 — we're rapidly approaching the show's endgame, which means that characters we love are probably going to start dying again, and alliances will be forced to solidify or shatter in the face of the Night King's advance on Westeros.

With that in mind, we spoke to Alan Taylor, director of episode 706, "Beyond the Wall," to discuss the developments of last Sunday's episode and the tensions rising heading into the finale — including the fact that George R. R. Martin was apparently dropping hints about his ultimate plan for the story way back in Season 1.

Taylor on location in Iceland Image: helen sloan/hbo

The last time you directed on the show was in Season 2 — has the experience changed much since then?

Yeah, it's funny; it's very, very different, and yet the same. The first two seasons, it had by no means the scale of audience attention that it has now, and when I came back after being away for a while, I sort of thought I'd be returning to the same enterprise. When I came back, I was immediately struck by how much bigger the whole thing has gotten. It was always big — there were always two units functioning simultaneously in different countries, so it was always a certain scale — but now instead of one bunker you walk by on the way to the stage, now there's 10.

The main difference, I think, is probably the certain story elements, like the dragons. The visual effects are a huge part of it in a way they weren't before. If you're doing one shot on a frozen lake with a dragon, it's actually seven shots that are being stitched together in various layers, shot in various ways to compose into the story beats, so it's a much more complex machine now than it used to be. But the funny thing is that the spirit remains the same. It still feels like an indie production. People are still completely unpretentious, including the actors and how they do the work. It still feels scruffy and rough and ready. It's got the worst craft services of any production I've ever been on — it's got two crackers and some cold tea. [Laughs.] It hasn't gotten bloated at all. It's still lean, but the finished product is huge.

How long did that final battle on the frozen lake take to film, all told?

Oh boy. I'd forgotten how many days we were there on that frozen lake, but I can tell you it felt like roughly forever. It was getting up pre-dawn every day, going to this quarry that was outside Belfast. The crew would be there already, sweeping whatever rain and stuff had happened off the ice and restoring the snow on our set, which was huge and 360 degrees.

I remember the DP — who is brilliant, Jonathan Freeman — despairing because he realized one day we had bright sunlight, which is horrible when you're North of the Wall, and fog, which is impossible to shoot in, and snow and rain all in the same day. He's trying to pull a coherent vision out of all those elements. Coupled with the fact that when Dany arrives, she's sitting on a huge styrofoam green thing on top of our [island], and you're shooting three layers of shot ... any time anybody goes through the ice, you know you're going to be shooting that later in a dunk tank on a sound stage. It was huge and insanely complex. We were there for weeks, and I know that the investment of my time was something I've never experienced in television. I think from my first scout of that location to finishing the episode took five months, which is way into feature film territory, not television.

I honestly had no idea you filmed the ice lake battle in a quarry in Belfast instead of in Iceland until I saw the behind-the-scenes video from filming.

Yeah, that was tricky. We knew we were going to be running around in Iceland for the most part for the first half of the episode and then have to find a way to transition to our ice lake, and we were lucky to find an intersection in this gorge that we were in in Iceland that could believably take us to this new set, so that worked out. We had to shoot the frozen lake close to home, because there's too much prosthetics and pyrotechnics and stunts that we couldn't do that remotely somewhere on location. We had to do that somewhere near base camp.

I’m so fascinated by the biology of the dragons – can you talk me through the process of what happened to Viserion after the Night King hit him and we saw that explosion from his throat?

A tremendous amount of thought went into them from the early stages. It was very important to David and Dan that the dragons be quintessentially believable. They had a huge disgust for dragons that had four legs and wings. Many times you see dragons rendered that way, and their point is that nowhere in nature do you see a creature that is built that way. So they were adamant that they had to have large hind legs and that the wings had to be elements of the four legs.

Beyond that, the biology of how you blow fire and what's the pilot light like on the inside of the throat ... One of the fun things here, and there's a lot of debate as to how much we could do it, was when he gets stabbed through the throat, he's trailing blood as he falls. He's also trailing smoke and flame as he falls. So he looks like a jet fighter going down. We were mindful of what the reality would be if you punctured one of these guys there.

And then a lot of thought went into the logistics of the scale of it; how much room is going to be required to arc around, how much ice will it tear up when it hits the ground? And besides all that, trying to make sure that it had a chance to play emotionally. One of my favorite shots is the one where Viserion sinks below the ice, and it's the one time we take a long time with the moment and let it stretch. We're in a full battle at the time, but we had to let that moment hang long enough... and the visual effects department did a wonderful job of realizing it, you feel the mass of the creature. It feels so lifelike in death. I think it really worked well.

There's also a lot of effort going into giving them moments of character. There's a tiny moment that probably not many people noticed, but when Dany and Tyrion are walking out to the dragons when she decides she's going to go off on this mission, they're just waking up from a nap. You see three dragons raising up in the foreground, and one of them shakes his head side to side. That's because our storyboard artist, who's kind of brilliant, who has two dogs, knows that when her dogs get up from a long sleep, they shake their head. You can see, I think it's Viserion in the background, doing that gesture. It's little observations like that to make sure the dragons are fully alive.

We see Jon and Daenerys share a moment of intimacy on the ship, but then there’s that subtle shift and Dany pulls away and shuts down on him – what’s going through her mind in that moment?

Certainly those who have read the books or are reading the books know that we've been heading in this direction for a long time. I've mentioned before that it was a revelation to me about the scale of George R. R. Martin's thinking that he came to visit the set in Season 1, when none of us knew what we were contending with really, and said a few things that made it clear that, for him, this whole epic thing — this story he was telling — all came down to these two and them getting together.

Of course, back then, none of us knew that. We didn't know that Robb Stark was going to [die] – he seemed like he was the heir apparent, and the fact that this bastard sidekick brother and this girl on a whole different continent were going to turn into the core of the show, we didn't see that coming yet.

I think we've known for a while that Tyrion is making fun of Dany, because he sees what's coming. I think there's a bunch of things at work in that scene, and they pulled it off wonderfully. It's just the right level of swooning for each other but drawing back. It was one close-up of Emilia that really tells that story very well, where you see her, she's going over the edge, and then she forces herself back when she pulls her hand back. It's probably because she's got a lot of responsibility. She can't be falling like this. Tyrion has already made fun of her for this, so she's got that motive to draw back. I think everybody understands it's pretty inevitable.

The tension in Arya and Sansa’s relationship is almost unbearable right now. How did you and Maisie approach that final scene between them from Arya’s perspective?

All my favorite scenes are the scenes between the girls. I think it's probably because I have two young daughters who spend a healthy amount of time hating each other's guts. Watching these two feel each other out and test each other and feeling the balance of power shift back and forth between them was a real delight. I remember reading the script and thinking, "Oh my God. It's eight pages, and they're just standing there. What are we going to do?"

We blocked it in a way that felt like it had a little bit of momentum to it, and there's a nice thing where they're turning the tables on each other. [In their first scene together, where Arya confronts Sansa about the letter] each one takes some time with the bloody carcasses hanging behind them... you really feel that they both have a case to make. What I also like is they're both legitimately lethal at this point, and we know that Arya can kill things at the drop of a hat. I think we're starting to realize that Sansa has gotten somewhere quite dark. She's learned a lot from Cersei, as she says at one point.

I love the fact that that tension is there, and I just wanted people to feel that you weren't sure who was going to kill who, but it was quite believable that either one could kill the other. There are things like the dagger in the scene between them and the fact that Brienne is being sent away to clear the deck so there's no police in town. The idea is to build up the expectation as much as possible that one of them is going to die, and hopefully surprise people by what happens.

Game of Thrones airs Sundays at 9 p.m. on HBO.