(Cover) - EN Showbiz - Kristen Stewart would "hyperventilate" over tough scenes when she worked with Dakota Fanning.

The two actresses starred alongside each other in the 2010 movie The Runaways, which was about the 70s female rock band of the same name.

Dakota portrayed Cherie Currie while Kristen, 21, was Joan Jett, and the stars had a lot of difficult scenes. Dakota's character struggled with drug addiction, and the two actresses also had to kiss on screen.

Kristen was amazed by how relaxed 17-year-old Dakota was during shooting.

"We had a few scenes that were crazy intimidating, and maybe once or twice, she was like, 'OK, I have a butterfly in my stomach,'" Kristen explained. "Meanwhile, I'm hyperventilating! Sometimes I give her sh*t for being so on the ball."

Dakota features on the cover of the February edition of Cosmopolitan magazine, after the publication named her the Fun Fearless Female of the Year.

It's a title which has previously gone to Mila Kunis and Anna Faris and Dakota hopes it is accurate. She's proud to be comfortable with who she is and the career path she's chosen.

"Since I was young, I've always known who I was," she told the publication. "I never really had to go through finding who I am. I've always felt really secure." (C) Cover Media