When Noomi Rapace won the role of the gutsy Lisbeth Salander in Stieg Larsson’s The Girl with the Dragon Tattoo films, she knew it would change her life. But not quite the way she expected.

“I thought everyone would hate me!” says Rapace, 30, who transformed herself into an androgynous, punky, chain-smoking computer hacker for the three Swedish movies. “The readers of the books have such a strong relationship with her as a character, I thought they’d never accept what I did with Lisbeth. It felt like a suicide mission to accept the role.” To prepare, Rapace trained kick-boxing four times a week for seven months, dieted, got a motorcycle license, cut her hair and pierced herself a total of six times.

Her 7-year-old son – with Swedish actor Ola Rapace – was at first hesitant about his mom’s new look. “For the first movie, he asked me, ‘Mom, why do you want to look like a teenage boy?'” she says. “For the last movie, I shaved my head on both sides like a Mohawk. I brought him with me when I did it, because I didn’t want to come home and look like Edward Scissorhands and scare him! He sat there and looked at me and said, ‘Mom, why are you doing this?’ After a while, he said, ‘I think it looks good! I want a hairdo like that, too!’ That’s when I said, ‘Stop!'”

Her efforts paid off, and the reaction to her performance was quite the opposite of what she had predicted. Next for Rapace? A role in Guy Richie’s Sherlock Holmes sequel, currently filming in London. “I’m so happy to be a part of this movie!” she says. “I’m not allowed to say what it’s about. But it’s a big honor and joy to be able to work with Robert Downey Jr. We have a lot of fun together! And I’ve seen all of Guy Richie’s movies and he’s a brave director.” And she’s looking forward to spending more time state side. “I feel you have more freedom to be individualistic here,” she says about comparing the U.S. to her native Sweden. “You can be a bit more extreme. It doesn’t matter if you walk down the street wearing sunglasses when it’s raining. No one cares! It’s a wonderful feeling. I love that there’s so much tolerance for individuality.”

As for the English version of the Dragon Tattoo films? “I’m not sentimental,” says Rapace who didn’t want to reprise her role in the David Fincher-directed movie, now starring Rooney Mara as Salander. “I wanted to move on. Lisbeth is no longer a part of me and it’s completely okay for someone else to become her. I’m sure it changed my personality in many ways. I did everything I could, and I want to continue my path.”