'Vikings' and 'Westworld' Star Gustaf Skarsgård on Growing Up Skarsgård (Exclusive)

Robby Klein/Getty Images

The 37-year-old actor tells ET that 'Westworld' is his most challenging project yet -- but he's used to the competition.

There’s nothing wrong with a little friendly competition.

With Stellan Skarsgård as a father, Gustaf Skarsgård didn’t have to work too hard to find himself on film sets as a kid -- but neither did his brothers. Of his five siblings and two half-siblings, three of Gustaf’s brothers also became actors.

There’s Alexander, best known for True Blood, Tarzan and his award-winning role on Big Little Lies; Bill, who captivated audiences as Pennywise in It; and Valter, who, at 22 years old, is still mostly acting in Sweden.

Gustaf also spent most of his career acting in Scandinavian films and TV shows, before making a name for himself with international audiences in History’s Vikings and now, the upcoming second season of Westworld.

“Whenever I say Westworld, there's a guy with, like, a laser side beam pointed at my chest,” Gustaf said with a laugh while chatting with ET on a rainy January morning. The 37-year-old actor first warned that he wouldn’t be able to talk much about the HBO series, but as a huge fan of the show, there were a few details he couldn’t help but boast about.

“It’s probably one of my favorite television shows of all time,” he exclaimed, admitting that after watching season one, he asked his management to do whatever it took to get him on the show. “They approached them and told them I was a huge fan,” he recalled. “I think it's so intelligent and aesthetically beautiful and I really think it's a great show. So I'm just flattered to be a part of it in any capacity.”

Gustaf will be playing a new character named Karl Strand, who he described as “an ex-military, white collar guy who works for the corporation.” The description sounds like Gustaf will be working on the Delos side of things in Westworld, but he wouldn’t confirm.

“They're so secretive, with the nature of the show, where there's so many plot twists and everything is so delicate,” he said, calling working on the show one of the most “challenging” experiences of his career.

“When I first joined the show, I got the script two days before I started shooting. And there's constant rewrites and a lot of stuff happening and changing all the time, so you really have to be on your toes. Your professionalism is constantly tested, because anything can change at any moment, and it does,” Gustaf confessed. “You can never relax and kick back. You really have to be on your toes, and be professional and private and deliver at the top of your game the whole time.”

“It's really challenging that way. But it's also amazing to be challenged,” he added -- though challenge is something he’s felt almost his entire life.

“There’s always [a rivalry],” Gustaf stated blunty, when asked if he feels competitive with his brothers. “Of course there can be jealousy and insecurities and whatnot, because that’s inherent in this profession as it is. And then if you have that close to you, within your own family, if your brother is doing great when you are not, that’s a reminder of that.”

The actor paused for a second, before continuing: “But that’s not to say that you can’t be happy for each other as well… Even if I’m at my lowest, insecurity and everything, I would still always wish the best for my brothers. But when you’re doing well yourself, you just have more excess of happiness for your brothers.”

Gustaf, Bill and Alexander at the Los Angeles premiere of 'It' last September. - Albert L. Ortega/Getty Images

With his new role on Westworld, Gustaf has an abundance of happiness for Alexander, Bill and Valter -- as well as for himself.

“I really do love it,” he raved, revealing that he’s been trying to piece together the season’s plot based on his own scripts. “Most of my questions have been answered, but there are still a lot of things I don't understand, and a lot of speculation within the cast. It's so funny, because people will get different information at different times, so we're working, but we're actually speculating together, like, what stuff could mean. It really is like solving a puzzle from within while you're shooting the show.”

And with him and Alexander now both part of the HBO family, Gustaf said he hopes a brotherly collaboration is in the near future.

“Obviously it has to be the right project and the right material, but I would love to. I think it's so much fun to work with people who you like and love and are close to,” he insisted. “I really hope that they will find a great project for all of us. That would be fun.”

Westworld returns April 22 on HBO.