For the self-proclaimed “Dostoevsky kind of guy,” actor Peter Mullan (My Name is Joe), Prime Video’s most-watched series, The Lord of the Rings: The Rings of Power, offered him a chance to tap into a whole new world, and filming in New Zealand wasn’t too shabby either! While talking with Collider’s Steve Weintraub, Mullan, who plays Dwarven King Durin III, discusses working with his costar, Owain Arthur, how the scope of such a groundbreaking series affected his preparation, and why he hopes no Lord of the Rings fans ever come up to him.

Rings of Power introduces J.R.R. Tolkien fans to the Second Age of Middle-earth, an era previously unexplored on-screen, in the time leading up to the forging of the rings. Not only does the show create a visually immersive experience based on the text, but it brings to life characters, both new and familiar. Mullan’s King Durin III is a character fans have seen in a blink-and-you’ll-miss-it moment in Peter Jackson’s first film, The Fellowship of the Ring, retrieving the Dwarves’ ring. In Rings of Power, he’s a fiercely protective leader whose desire to protect his own clashes with his son, Prince Durin IV’s (Arthur) call to support the Elves. The series’ ensemble cast also features Morfydd Clark as Galadriel, Sophia Nomvete as Princess Disa, Charlie Vickers as Halbrand, and Robert Aramayo as Elrond.

When the Elves first come to the Dwarves for help, King Durin is hesitant, but willing, until his own people are lost to a dangerous mining operation. In Mullan’s interview, which you can watch or read below, find out what he would have done with the mithril in that situation. They also talk about why Mullan’s approach never changes, no matter the size of the production, why he didn’t discuss character relationships with Arthur prior to filming, and how deep into Tolkien’s lore Mullan really is (hint: it isn’t quite as deep as the Balrog’s home beneath Khazad-dûm).

COLLIDER: I've been a fan of yours for a while, and I'm curious, you've done so many things, if someone has actually never seen anything you've done before, what is the first thing you'd like them watching and why?

PETER MULLAN: Probably My Name is Joe because it's a good, very nice film made by a genius director, Ken Loach, and filmed entirely in Glasgow where I live. I would recommend that they watch that, and that's the one they gave me the big prize for way back in the day, when they gave me the actor prize at Cannes. So, even if someone doesn't like it they can go online, and they can say, “What? They give him best actor for that?” So, I would recommend that one.

Your character makes a decision to basically let the Elves die, and I'm just curious, do you personally agree with that decision, or would you have given them the mithril?

MULLAN: I absolutely agree with that decision. They’re boring as all hell, and kill the Elves! That comes from the Dwarf. King Dwarf says the Elves deserve everything they get. They're too big, literally and metaphorically. Get rid!

[Laughs] Not the answer I was expecting, but I appreciate the humor. Listen, I love the series and I'm blown away by the scale and scope, it's like an eight-hour movie, it's not a TV show. What was it like for you actually, because you've been involved in so many different things, what was it like for you stepping on set for the first time and realizing what this thing was gonna be?

MULLAN: Well stepping on first time, it was kind of tricky in the sense that I hadn't been given the scripts. I only got the scenes that I was in, so I've got no context, I don't know what anyone else is doing, I don't know what size it is. I knew it was big, but then Harry Potter was big. I mean, so what? Big deal, you know? Just because something's big doesn't mean to say it's going to be any good. So, walking on the set was interesting because, it's like any big sets that I've been in; you reduce it mentally and emotionally as an actor, you reduce it to your lines and your fellow comrades, your mates, your actors. And so, you make the world very, very small because you need to because you're going to climb up a very big mountain. If you allow the size of something to get to you, then you'll freeze, you'll choke, you'll panic. So it's vital to be comfortable with your fellow actors, and with the crew and with the director.

So personally, what I would always say to any actor in these big sets is make it very small, have a laugh, take the mickey out of it. Don't take it too seriously, and that way, come the serious moments, you can explore the same way as you would if you were in a no-money production. There was a guy who said to me years ago – and I don't normally pay much heed to wise folk in the industry telling you wise things, they usually tend to be dicks – but this guy did say one thing that really stuck with me, and it was, “Professionalism is not a standard, it's a state of mind.” And he was right because if you're in a low-budget film, you should be given just as much attention and just the same amount of effort, and exploration as you do in a big budget production. Money shouldn't come into it, size shouldn't come into it, so if you have the same attitude in a low-budget production as you do in a big-budget production, then you'll have your own working method that's true to what you're doing. And I think that's something sometimes actors, not necessarily young actors, but some actors, let the size of something get to them, and they feel that they should somehow fill that space, and that's a mistake.

Where we were lucky in Lord of the Rings was that the directors made us all feel very much like it's a low-budget, student production. They kept the scale at bay, and you have to do that because if you don't, you will get performances that have no basis in any kind of truth. They're just based on fear because the actors are terrified, rightly so. The actor’s thinking, “Shit, I don't deserve a big trailer or a big set or a big, fancy costume. Who am I?” You know, so you immediately doubt yourself. So, we were really lucky in this to walk on those sets and it not be a big deal. You want to familiarize yourself with a set in relation to what you're doing, but you don't want to spend too much time looking at it going, “Wow, this is amazing.” You don't wanna do that ‘til maybe after the first week when you're feeling alright.

You and Owain are fantastic together, and I'm just curious how much were you guys talking before you stepped on set about your relationship and building a bond, and how much was it just that you guys are good actors?

MULLAN: That’s it, it’s the last thing.I think we can act, and we both know it, and we didn't do any talking about it, or any of that stuff. We just got on really well, and we trusted one another. The only thing I know about acting is never tell another actor what to do. That's the only thing I know. Now a director comes in, they can tell you, “More of this, less of this,” whatever, but the only thing I know about acting is I would never tell another actor what to do.

So, if an actor wants to talk about things, absolutely, I don't have any problems, but I would never suggest or move it. If they're going to be a light bulb, I'll be a lamp shade, and if they want to be the lamp shade, I'll be the light bulb, and if they want to jump between the two during the scene, fine by me. I mean, I love the fact that between the word action and cut, you can go wherever you go. It's as [Robert Frost] said about creativity, it's a big block of ice on a hot stove, it'll go wherever it goes, and acting, for me, should be the same. Just go wherever it's gonna take you. Sometimes you do a wet performance and you cry your eyes out, and the next take, you do a dry performance and there's no tears. Who knows which one's better? Give it, and the rest is up to the director and the editor and stuff. So with Owain and I, we had a really lovely trust and respect, and other than that, we just played the scenes. It was great, he's a beautiful [actor], lovely.

I'm curious, how familiar were you with Tolkien's work prior to getting cast, and how much did you feel, because Lord of the Rings is so beloved by so many people, that you wanted to read everything and learn about the history so that when fans come up to you, you could sort of talk about it?

MULLAN: Oh, well, I would hope no fan would ever come up to me because I don't have a clue about Tolkien or his world [laughs]. It totally passed me by, and I've got mates that love it, know it inside-out. I wasn't a Lord of the Rings kind of guy. I would be more Dickens and Shakespeare in terms of the classic, and Dostoevsky, I was more a Dostoevsky kind of guy! Lord of the Rings? Never, no, I had no feelings one way or the other for it. I liked the first film that [Peter] Jackson did, other than that, I didn't watch any of the whole bits or the other ones. I didn't know anything about the world at all, but I liked the idea of doing– well, I loved the idea of going to New Zealand, and I loved the idea of just doing something that involved all that kind of silliness, you know?

Season 1 of Rings of Power is available to stream on Prime Video. For even more on the series, check out interview with J.A. Bayona, the director of Episodes 1 and 2, below, and be on the lookout for more from the cast and crew!