[Laughs.] It's funny, actually, we had a really old-school personal trainer named Pat Henry. Pat Henry has trained tons and tons of people who've gone through Dublin and made films in Ireland. He's a wonderful man … He took us all under his wing. He took myself and Diarmaid Murtagh, the guy who plays Brastias, and Peter Mooney, the guy who plays Kay, and Clive Standen, who plays Gawain. He took us all under his wing.

He kind of made this thing we called the knight workout. And we were doing things typically that would be helpful for your upper body for sword fighting and riding horses and things like that. It wasn't as much as “Crusoe,” because I remember on “Crusoe” we were running sand dunes and doing things like that. We weren’t doing pull ups on the castle by any stretch of the imagination, but the workout with broadswords and then horse riding, and training with Henry was a different workout.

Each show kind of has its own flavor; each character needs to look at bit physically different from another character. So hopefully you get a couple of months or at least a month to try and change your body enough to become those people in a way that is more believable.

You seem to do all these very physically demanding roles. Is that something you try to do?
I could be looking for them, I guess. When I read the scripts I see that there's the physical stuff in it. I just know that I enjoy it. I enjoy doing it and I enjoy the challenge of how it’s shot. Obviously what the audience sees is the character having a great sense of himself or of looking a certain way. But it's a huge collaboration. You have your personal trainer, you have your nutritionist, you have the camera team and the director picking the way you're going to move and the things you're going to do in the scene. So it is really a huge collaboration. And it’s lovely when it comes across on screen and people think, “Gosh, we really believe that.”

Let’s talk about the cast. How scary is Eva Green for real?
[Laughs.] Eva Green, she was actually just lovely. She is such a lovely person. … To be honest with you, she is such a treat. She's so professional and she's breathtakingly gorgeous. So can you imagine Eva was up there and five, six, seven of these knights hanging around with each other, it was just—usually there was tons of banter going back and forth with each other and then Eva would step on set and you could hear a pin drop.

That's funny. She's really good in that role.
She's fantastic, isn't she?

Yes she is. You have a lot more with Joseph Fiennes and the knights.
Joseph Fiennes, he is fantastic. We had such a crack, especially being in Ireland where the atmosphere on the set, there was always a lot of banter going on between each other. We made fun of Joe being Shakespeare [in “Shakespeare in Love”] and things like that. He was brilliant. He’s such a good actor and made these great choices with Merlin. It was so great to stand beside him and watch him do things with this character. You just think, “Gosh, this guy is really good at what he does.”

But honestly the time we spent together as a group of guys, the knights, was great. Not only did we spend a bunch of time together on set, because the shooting hours for episode of television are just long and arduous, but we spent a lot of time in the pub. We spent a lot of time training. We spent a lot of time horseback riding. And if we weren’t on set, we were probably either out learning lines or doing auditions with each other or hanging out at the pub and watching rugby and just kind of getting a bit of the culture down. So the relationships were really deep. And that's why it's great to have more here now in Cape Town. It feels like this brotherhood kind of got back together again, because it's been a few months since we've seen each other.

Ireland looks gorgeous in the episodes. Did you get time to really see it?
It's just so magical. It's absolutely brilliant. People in Ireland are just so hospitable. ...

Did you shoot in real castles or were those sets?
They were sets. They did a fantastic job. It was over at Ardmore Studios where they’d done “The Tudors.” Morgan O’Sullivan … is just a wonderful producer. He's been doing it for years and years and years. Everyone respects him so much because he's kept the film business alive in Ireland. He brought in this amazing team of production designers. And they built the castle inside one of the sound stages; the great hall was inside the sound stage. And the exterior shots, they usually built the door, and a bit of the wall and then green-screened the rest of it on a cliff outside in the Wicklow Mountains just outside Dublin. So we did a lot of exteriors out in the mountains around Dublin, which was equally beautiful because I never imagined Dublin to be so rugged and vast. But it really is. You can drive outside Dublin in half an hour and you're in the luscious, greenest mountain you've ever seen. They're just beautiful.

 Are we going to see Frank again on “Fringe”?
I don't know is the real answer. It was funny, Frank came in about a year ago. And I got to meet with everyone and do some scenes with Anna [Torv] and stuff and we had a ball. And I was really pleased, and surprised to be asked back again and we developed the character a bit more. Then this big bombshell happened in the last stuff that I shot. [From Curt: Frank learned Fauxlivia was pregnant, with someone else’s kid.]

It was funny because I was filming “Camelot” and I would leave “Camelot” on a Sunday morning, get to Vancouver … Sunday night. I'd film Monday on “Fringe” and I'd fly back to Dublin on Monday night. So I would literally be in Vancouver for about 24 hours.

Shooting for 12 of those, probably.