"Working this closely with someone, you can't help but really become bonded with them and it really helps when you actually like them and can become really good friends," Stewart said Wednesday during a press day for the movie about the '70s all-girl’s band in which Stewart plays rocker Joan Jett and Fanning, singer Cherie Currie.
"I haven't really done a lot of movies with people close to my own age to have a good friend like that," she said. "So I was excited, and I couldn't have asked for a better person to do it with."
Stewart and Fanning lock lips onscreen, which the two say wasn’t awkward one bit.
"It was cool. I didn't mind it," Stewart said. "The way that it happens in the script is so just a sort of moment in time and fun and natural and sort of impulsive."
Adds Fanning: "It was just another thing."
So who did Stewart think was the better kisser – Pattinson or Fanning? "I don't know," she says. For now, her lips are sealed.
Reporting by SCOTT HUVER