Alexander Ludwig on his 'Vikings' debut and playing a real legend

All hail Bjorn Ironside! The first-born son of Ragnar and Lagertha makes his debut Thursday night — well, his second debut — on History's second season of Vikings, as Alexander Ludwig takes over the role of the older, stronger Bjorn (played in season 1 by Nathan O'Toole).

You'll recognize Ludwig from breakout roles in The Hunger Games and Lone Survivor, but it's his new gig as the quiet and obedient son of Travis Fimmel's raging Ragnar that should make Ludwig pop onto your screen. Before Thursday night's episode (10 p.m. ET on History), Ludwig stopped by EW's office to chat about his latest role as a lost Norse legend.

ENTERTAINMENT WEEKLY: Was it difficult transitioning into an already established show like Vikings?

ALEXANDER LUDWIG: It's been very, very effortless, and great to be a part of a show that's already been established as successful, because you don't have to worry about what's going to happen. But I've been so happy with the way I've been received by the fans and I think they're really excited to see what happens with Bjorn.

On that note, what does happen with Bjorn?

This entire season is really about finding his place in the Viking community and laying down the foundation for the legend of Bjorn Ironside. You see him come into his own as a young man and build the legend. He was a real guy, and arguably did more than his father before him. Honestly the story of Vikings…it's amazing. Ragnar Lothbrok was a legend but his sons went on to do great things, so I'm really excited to see where the show progresses and if we will see that angle where Bjorn goes on his own voyages and creates his own legend. If you want to have a little bit of a spoiler you can look him up because what he did was incredible.

What's the biggest challenge when it comes to filming a show like this? Is it the physicality?

I wouldn't say physical. I had experience in that field and that definitely came into play, and that's what I love about the show — it really doesn't glamorize the fighting. It's not very Hollywood, it's very edgy and raw and it's not played up by any means. But I think one of the greatest challenges was coming into a show where you're playing off of someone who has already been established in the first season. I definitely struggled with idea of keeping a lot of [Bjorn's] fundamental characteristics: he's quiet, he's sincere, and I like playing off that because I think Bjorn commands a lot of attention, in that when he talks, people expect it to mean something. And when he smiles it's a big deal.

Did you have conversations with Nathan, who played young Bjorn?

I watched everything that Nathan put on screen in the first season and I definitely took that into account, but at the same time I came to the conclusion that four years has passed since you've seen him and he's not a young man — even I'm not the same guy I was a year ago. A lot can change, and he's trying to grapple with a lot of conflicting emotions and that was really fun to play with.

How does the cast kick back off camera?

After they say cut it's like one big party. Travis and I will be wrestling off screen and we all sit in this tent together and play little games and everyone gets involved. We genuinely love each other's company, and if anything it just helps with our chemistry on screen.

What else might people be surprised to know goes along with a show like this?

The whole crew really works together to power through the day — we don't break for lunch. Another thing: before the fight scenes, we spend maybe two weeks with fight trainers and stunt coordinators. By the time the director says action it becomes a s–t show. Like, everyone forgets everything, and you're swinging and trying not to get hit and you're trying to remember what happened and you always come up bloody one way or the other. It's really fun. At the end we'll always [try to figure out] who got hurt the most.

You're no stranger to passionate fans thanks to The Hunger Games. How do Vikings fans compare?

It was interesting doing a film like The Hunger Games because we all knew it would be successful but we didn't know just how much. The weirdest experience for me was becoming a celebrity before the film even hit screens. People would be trying to sneak onto set and it just snowballed from there. Now with Vikings and Lone Survivor, I've really gained a different audience but kept my [fans] from Hunger Games and that's been great. On the Vikings set in Ireland, people don't get as excited about celebrity, but we still have people trying to sneak on set. And when I come back [to America], it's nuts. I've been really pleasantly surprised with how well the show has been received even with the younger audiences, especially amongst young girls, and I think it'll only grow. There are some really badass female characters and they're only going to grow as this season continues.