'Twilight's Kristen Stewart, Joan Jett onstage at Sundance

Asked earlier in a press conference how she felt about playing Bella vs. playing Joan Jett, Kristen saw similarities and differences.

"Bella's effect on the world wasn't necessarily as great as Joan's, obviously, and I never got to meet Bella," Stewart said. "It's completely different. All these people who have an investments in these women, that's awesome...but when it becomes personal and it's my responsibility to not destroy, like, what people are going to take from the most important part of my friend's life"

"Joan has become really, a really big part. She's awesome and I really love her. If we hadn't told the story right, people don't know the Runaways in our generation. Because they're going to see them through us, it's a much different experience than making an original fictional story."