Charlie Endean has what he describes as an “unusual role” on Game of Thrones. As the head of the department for the show’s assistant directors, he’s used to people seeing his title and assuming he’s a glorified production assistant. But his job is much more complicated — especially on this series. “There’s a big team of us who work very closely with the director and the producers,” he told The Verge via phone from Belfast, the HBO series’ home base. Fresh off a 10-hour planning meeting for Game of Thrones season 8, he explained his responsibilities: “You sit directly at the crossroads of the director’s vision and the production’s budget. Your loyalty is to both.”

On Game of Thrones, that means coordinating with the heads of every team involved in a given scene — set design, costumes, hair, makeup, stunts, pyrotechnics, digital effects, and more — and keeping them all aware of what the director wants, from the earliest script breakdown to the actual shooting days. Endean is an experienced first AD, with credits on the British series The Midnight Beast, The Last Kingdom, and Tatau, and the Irish / Canadian co-production Vikings. On season 6 of Game of Thrones, he was first assistant director on the final two episodes, “Battle of the Bastards” and “The Winds of Winter,” both with director Miguel Sapochnik and cinematographer Fabian Wagner.

This season, he pulled off a similar double feature with the back-to-back episodes “The Spoils of War” (where Daenerys Targaryen and her black dragon demolish a Lannister army) and “Eastwatch” (where her friends and enemies decide what to do with themselves in the aftermath). Both episodes were directed by Matt Shakman, with cinematography by Robert McLachlan. After speaking to McLachlan about designing and shooting the “dragon-induced Armageddon” in “The Spoils of War,” The Verge followed up with Endean, to discuss behind-the-scenes stories from “Eastwatch,” why Game of Thrones is “a unique animal” for a first AD, and how the series is getting more complicated and demanding for the crew as it nears its conclusion.

This interview has been condensed and edited for clarity. Spoilers for Game of Thrones season 7, episode 5, “Eastwatch,” ahead.

How much do you personally get involved in aesthetic decisions on your episodes?

It varies from director to director. Matt Shakman was very creatively open, which was a pleasure, because you’d get to suggest ideas and be a sounding board for ideas. But ultimately, you’re there to ensure that a director’s vision is being achieved accurately.

Was there any particular idea or note that you were proud to bring to these episodes?

It’s hard to say, because so much of what you discuss ends up being part of a boiling pot of many, many ideas. I’d hate to take credit for someone else’s idea. One of the things Matt and I discussed at length was the images of Dothraki bursting through flame. We looked at references of Spanish horse-riding festivals where the riders would drink heavily and then ride. They’re insane men, these mad Spanish guys who’d ride horses through bonfires. The visual references were so tantalizing, so I found a lot of those photographs and shared them with Matt, and that inspired us to think, “How can we achieve that without endangering a horse, but still get those horrific, iconic images?”

When the show goes to a place it’s never been before, like the Eastwatch cell block, how does that affect the episode budget, since that’s something you aren’t sharing with other crews?

The Eastwatch cells were a recycled set that we refurbished from something we already had. I don’t remember what, sorry. What was important there in the design was that Matt wanted the sense that the prisoners were absolutely freezing, and that it was a drafty, cold space where light kind of dripped in on them. So Rob [McLachlan] and Matt spoke very carefully about how to achieve that. We ended up creating a kind of grille above the characters, so the light would leak through like in jail, but from above. And then they dressed icicles and a small dusting of ice around the characters, so you didn’t see them until they leaned in from the ice.

Where was that scene shot?

It was shot in Belfast. An enormous amount of the work we do on Game of Thrones is here in Belfast, because we have a huge studio system at the Titanic Quarter. They were old shipbuilding spaces that were converted into studios, because they have astronomically high, huge gated doors that roll back to allow huge pieces of set or equipment to come in.

Were there any particular budget challenges for “Eastwatch”?

Whenever a dragon appears, it’s expensive. And it’s a tricky one, too. The fans love them, but honestly, they’re very hard to work with. An actor is trying to act quite often with something that isn’t there, so they’re being challenged to emote while looking at a green screen, or a piece of green cloth. The sequence where Jon meets Drogon, we were filming on a cliff-edge in Northern Ireland, with very high winds, and Kit [Harington] had this safety rope attached to him, and a harness, because it was so windy. [Laughs] He had this heavy cape on, and had the wind picked up any more, he would have just turned into a human kite.

So you have him standing on a cliff-edge with a flapping cape, and a guy dressed in wet-weather gear, because it’s freezing, holding up a green ball on the end of a green stick. And that’s the dragon. It’s quite crude, actually. And then obviously everything is added in post. It looks preposterous, but you have to treat it seriously and create an atmosphere on set as if you’re at the theatre, while there’s all this anarchy going on. That’s an important aspect of what the assistant director is. What I have to do on set is make sure the machine moves fast, but the moment the camera rolls, you go into that quiet mode. Otherwise, nothing gets done.

For the Tarly execution at the beginning of “Eastwatch,” you had to create that serious atmosphere for a large crowd of extras who are all trying to pretend there’s a dragon on the hill above them. How do you approach that?

You treat people respectfully, and include them in the sequence. I really wanted to enforce that the extras got to see the previsualization. The pre-vis is produced after we do storyboards — with a big sequence with loads of CG, you turn the storyboards into a form of animation, but a very sophisticated one. And that is our moving shooting bible. Eventually, you can see the sequence before you’ve filmed it, which is hugely revealing from a budgetary point of view, but also from a dramatic point of view. You haven’t committed to filming yet, but you can still judge it. We screened that for the extras, who had signed NDAs and had their phones taken off them before they went in to watch it. They watched the sequence before they partook in it. That was tactically what we did to include people.

Is that unusual on a TV show? Is it usual for Game of Thrones?

I think they did it for the first time on “Battle of the Bastards.” It’s one of those things that I genuinely think improves a sequence, when everyone has an understanding of what it is.

In “Spoils of War,” you set a huge group of stuntmen on fire, but they could be relatively anonymous and shot from a distance. Here, you’re burning two familiar actors, with the camera up close. What was involved in coordinating that?

We shot up to the point of the actual burn occurring, and then switched to stuntmen who had facial casts of the actors. And then those face molds were turned into fireproof masks. So although they look like the actors, they looked like those actors had put on about three stone in weight. [Laughs] They really looked like them, but like they’re very unwell versions of them. But you never use them in the fat-head masks on camera, just once they’re alight. There’s a natural overlap where you can trick the audience.

What else was a challenge in “Eastwatch”?

The sequences on Dragonstone where Jon sails away were done on this incredible beach in Spain, and we chose it because, geologically speaking, the rock formations are stunning. It’s like nothing else. You could spend fortunes doing that with visual effects, but this site actually exists — the producers on Thrones are incredibly good at this, when they commit to an idea fully, when they think it’s worth it. So they said, “This is a beach that’s worth us going to.”

But what it meant, going there at that time of year, was that we were fighting the tide. Normally, we have a 10-hour filming day. There, we had like six and a half hours. We started with the cast at the lip of the beach, maybe 400, 500 feet from the cliff. And by the end of the filming day, you were fighting for space to put your feet on the sand, because the tide had come in so much, and it was very rough. So we were often having to cut mid-take, because the cast were getting washed away. So what you see as a tiny two-minute sequence cost us days of filming, and we were all wet up to the waist for most of it. But you anticipate these problems, you always make sure it’s safe, and you allocate time to it.

How did you approach the reveal and return of Gendry?

We wanted to give him a sense of mystery. Matt was specific about that. He wanted it to be almost a montage. You’re in the Street of Steel, you’re surrounded by weapon makers and weapon salesmen, and you could almost lose him in among that. But you wouldn’t just reveal him in an obvious way. You wanted something with a little tension and allure.

Matt had a really lovely approach. He wanted Gendry to be seen as a man who understood weapons, as a talented blacksmith. Not only do you see Davos having this fatherly affection for Gendry, you see Gendry is ready to go with him. And he has this phenomenal weapon that he’s crafted for himself, which is quite unique. That comes out of the fact that he’s a blacksmith, and we find him in his world.

How did the team decide what they wanted Gendry’s battle-hammer to look like?

David [Benioff] and Dan [Weiss], the creators, are very specific in a lot of their ideas. They trust the heads of department enormously. They would almost refer to crew members in the script. So Tommy Dunne, the head of the armory department, he and his team handmake all the weapons you see in Game of Thrones. They make real versions that are metal and weighty, so they’re perfect for close-ups, and then rubber versions of different weights for different fight sequences. With anything that’s going to be seen repeatedly on the show, Tommy would offer up multiple designs for feedback, and then a mock-up will be made and sent around to the various departments. So stunts would feed back on whether it’s the right weight, or it’s long enough for the fight sequences that have been planned. The creatives would also give their input. There’s so much feedback, and that’s on every item. [Laughs] There’s a load of talking.

What else stands out about this episode, and your role in it?

We’d just done “Spoils of War.” And when you oscillate between a very big sequence and something that isn’t so dynamic in terms of action, the important thing is to watch the details. So episode 5, “Eastwatch,” has a lot of interesting character moments and delicate pieces of information that need to be placed in such a way that they’re obvious. So it’s keeping an eye on those, making sure they’re revealed to the audience in a measured fashion.

There are lots of things in there — visual echoes. When the boys go out past the Wall, it’s a clear nod to the poster for 1969’s The Wild Bunch, a classic, iconic frame.

What’s the start-to-finish job on an episode like for a first assistant director?

You want to ensure that the director’s perception of the script is visualized to the highest standard. You also want to make sure that you protect the production, and bring that vision in on time. So it begins by breaking down the script, scene by scene, beat by beat, into its component parts. That could be anything from what’s written on a scroll in a character’s hand, and whether you see the writing, to how long a section of pyrotechnics rigging will take to set up, and then how much the aftermath of an explosion will take the art department to dress up.

I’m the head of the assistant directors’ department. That’s a huge team that is on both Game of Thrones crew units, Dragon and Wolf. They work tirelessly to support the directors’ vision. The team includes the second ADs and third ADs, right down to the runners. These are the people communicating the directors’ vision to anyone who’s unsure of what’s happening on a day-to-day basis. As you break down the scripts, you work out which parts pertain to which department. So if you have a huge stunt sequence, like in “Spoils of War,” you go through with the head of the stunt department and break down their responsibilities for a sequence. And the same with makeup, costume, set dressing, and so forth.

Is there competition between the show’s Dragon team and Wolf team?

There’s healthy competition, but not an unsavory one. Dragons stay in Belfast, and Wolves go abroad. That’s the division. But that doesn’t necessarily mean everything you see in King’s Landing or Iceland is Wolf, because a lot of the interiors or the SFX work would be interiors, so Dragon would take care of it. They work closely together, because they’re finishing off one another’s sequences quite often. There’s a camaraderie there.

How is Game of Thrones different from other series you’ve worked on?

Thrones is a unique animal. Normally when you have a TV schedule, one team starts to prepare, and once they’re filming, the second team starts preparing. So you top-and-tail. Thrones is different, because you all start pretty much the same time. You might have four or five teams — director, DoP, the first assistant director, and the second AD. They make up one team. Each team is allocated a color, and they are boarded across a very complex schedule, across many countries. We all share resources, and that breaks down into actors’ availability and sharing certain large pieces of equipment, such as cranes and sets.

This schedule gets even more complex, because you’re not just understanding your own scripts, you have to feed into others. And that means you need to understand all the characters’ throughlines and stories, because Dany might be filming something from the end of episode 3 on Monday, then on Tuesday, she could be filming something from episode 6. So her journey needs to be tracked, and made very clear for each story day.

What kind of decisions do you have to make as you’re balancing conflicts between ambition and budget?

It’s less a conflict, and more a series of small negotiations. One sequence that was spoken about in great detail was the loot train in “Spoils of War.” We had multiple dragon strafing runs to blow things up, but it was very expensive, and time is money on a film set. To allow the pyrotechnics team to rig a set, you have to leave it, and that costs you time. You can’t be on the set when it’s being prepared, so you have to move an enormous crew away. Then once you’ve blown it up, you need to dress it again, to make it look like it’s been blown up. So you have to balance the cost of multiple attack runs with how it’s going to look, and the time it’s going to cost you to have all these different stages of set dressing. Those kinds of fine details require an awful lot of negotiations and planning. So you involve all of the [heads of department] and get their opinions, and they find the strongest throughline and the best plan that accommodates every department. And that becomes your shooting schedule.

As the series moves toward its close, plotlines are coming together and the story is moving much faster. How does that change your job?

There’s a lot more information to track. You just have to be mindful of it. As the season develops, the storylines narrow, so all of the characters tend to be getting closer, and appearing in more scenes together. That adds a challenge, because earlier on Game of Thrones, you had so many stories and characters, it was easy to share actors. Now they’re all in so many of the scenes that you can’t share as well, and it’s harder to manage the resources.

You’re currently working on season 8. Are there new challenges there that you hadn’t encountered before? It seems like the show crew has built a machine and has the process down.

Yeah, the machine is definitely down. One thing you can say going forward is that on Thrones, you feel like you’re working with the best of the best. You trust the people around you, because at this stage, they’re friends as well as colleagues. That brings a degree of trust that you don’t get when you just turn up on a show. And that trust feeds back into the quality of the work. That said, you are always being challenged by the writers on Thrones. They look after their characters so well in the writing, but the challenges and sequences get bigger every year. So although the teams are strong, what’s being asked of them each year is more challenging. But that’s great! It keeps you interested.