There’s political upheaval in Khazad-dûm.

Following the seismic events that shook the Dwarven underground kingdom in “The Lord of the Rings: The Rings of Power” season 2 finale, which saw King Durin III sacrifice himself in order to deal with an unruly Balrog he’d accidentally awoken, Prince Durin IV was anointed his successor. But in step Thrain, Durin III’s older son — and technically the rightful heir — to challenge for the crown, sparking a major power struggle and fallout.

Played by veteran British actor Eddie Marsan, Thrain is one of the most notable new additions in the third season of show, which launches Nov. 11 on Prime Video. And while it may be Marsan’s first on-screen adventure into Middle-earth, he’s no stranger to Tolkien’s world. As it happens, “The Lord of the Rings” has been a major part of his family’s life for more than two decades — to the extent he once had several thousand pairs of Orlando Blooms prosthetic Elven ears stored in his house.

Speaking to Variety, Marsan explains his meditation routine during the lengthy make-up process and why he only joined the show to take the piss out his friend Peter Mullan.

But how did it feel joining ‘Rings of Power’ and like donning the armor of Thrain and and the dwarves deep down beneath the mountains?

It kind of felt slightly inevitable, really. My wife Janine [Schneider-Marsan] was a makeup artist on the original Lord of the Rings film. So I was shooting “Gangs of New York” and flew out to see her in New Zealand, and we spent some time together. And she kept going back for years afterwards to do the sequels and do pickups. So it was part of our early marriage for three or four years.

That’s fantastic.

She did the makeup for Orlando Bloom and Liv Tyler. And in our old house, in the loft, we had around 2,000 pairs of Orlando Bloom’s ears.

What do you do with 2000 pairs of Orlando Bloom’s ears?

I was going to bring them to “Rings and Powers” to see if they wanted them! But it was all part of our family life. And I also watched the show, because Peter Mullan is a very good friend, and I really loved the end of the second series when he sacrifices himself. I thought it was incredible. And then they came in and said, “Would you like to play Peter’s son?” And it was two things. I wanted to do it because I thought the show was brilliant, the writing was great, the direction was great. I thought the action was amazing. But also to be able to take the piss out of Peter and tell him that I’m playing his son.

Ha! How did he take to that?

He didn’t take it too kindly.

So was it a straight yes when the offer came in?

Yes. I mean, I look like a dwarf. But no, it was a straight yes. I wanted to do it. I knew that Peter had done it and Rory [Kinnear] had done it, and I admired their work in it and I was a fan of the show. Also, I love to mix things up. I love to do something that’s completely different to what I’ve done before. I have very little control over other aspects of my career, like whether you’re going to be in fashion or not, whether you’re going to be the hot new thing or not. All that comes in and out. You’ve got no control over that, but what you can control is the content — whether I always do something that’s completely different to what I’ve done before. So I came out of “Rings of Power.” Then we shot the second series of Netflix’s “Supercell.” Then Netflix asked me to be J. Edgar Hoover in “Kennedy,” which I did. So my approach to it all is to mix it up as much as possible. That’s what I enjoy.

You’re you’re playing Thrain. How would you describe him and how he fits into that sort of complex politics of the Dwarven kingdom?

Well, he’s the eldest brother of Durin the fourth, played by Owain [Arthur], and he’s the eldest son of Durin the Third, which is Peter Mullins’ character. And he was overlooked. He feels like he should have been the king. And his younger brother, was made the king. So in many ways, he’s kind of like Fredo in “The Godfather.” So at the beginning of episode three, he comes back to Khazad-dûm to kind of reclaim his crown.

Did you dig deep into Thrain’s timeline and history? He doesn’t make it to the ‘Lord of the Rings’ films, but I think there’s a there’s a deleted scene in ‘The Hobbit’ films that he’s seen in.

They gave me a a kind of backstory. I do like to have a kind of a backstory for a character that I can allow to inform my performance. So I used them quite well. They had really good specialists who you could always go to and ask.

What was the make-up situation like to get Thrain’s nose and beard on?

The whole team were amazing. They were getting at like 2 in the morning. I’m getting around 3 and sometimes you’d have to be ready on set about 7.30. So there were 4 1/2 hours of makeup. I meditate today and my meditation stretches to 40 minutes. So I’d have a 40 minutes meditation and come out my meditation with a big nose and big ears.

One of my fears of doing something with such big makeup was that the performances would have to be big. I’m not a very big performative actor. It’s not something I’m comfortable with. And then I began watching and working with Owain and Sophie [Nomvete], and I saw that their performances were so natural — not minimalistic, but free. They weren’t pushing it too hard. I realized that I could sit in and relax and just act it like anything else, and it would come through because the makeup was so good. So within the first week, I suddenly felt really comfortable.

This show’s in its third season. How was it joining something when it’s kind of already so far in?

It was great, because I already knew so many people. Kevin Eldon is an old friend of mine. And Owain and I had workshopped a theater piece years ago. I’ve been a big fan of his for years. And Paul Hickey was in it, playing one of the villains I think. I’ve been in the game so long so I turn up and know everyone. I also knew half the crew. The makeup designer — knew her when she was a young girl because she’s the niece of Peter King, who designed the makeup for Lord of the Rings, and he’s my daughter’s godfather. So that’s what I mean. It was part of our life, really. I was connected to it before I joined this series.

Given that “Lord of the Rings” has been a part of your family’s life for so long, if you’d have been able to pick any character to play, who would it have been? Would it have been a dwarf?

I think I would have liked maybe to play one of the Hobbits. I think they were great. I ended up subsequently working with a lot of those actors. But Thrain is a great character, he really is. It was a great joy to play him.