In her recent interview for Teen Vogue, Dakota Fanning says the following about her relationship with Kristen:

Making New Moon also gave Dakota a chance to get to know Kristen Stewart before they started shooting the upcoming Runaways biopic. “We became really close,” Dakota says, “like we’d known each other for our whole lives. We talk all the time.” Their off-set friendship added a layer of peculiarity to the proceedings on the New Moon set—”I’ve never been such an evil character, and because I do know Kristen so well, being mean to her was really weird. It’s like, Sorry, dude!” But the chemistry came in handy when Dakota and Kristen played punk rockers Cherie Currie (the Runaways’ lead singer) and Joan Jett. “The relationship that Joan and Cherie have in the script is kind of the one that Kristen and I have in real life,” Dakota says—although, she clarifies, “minus the destructive part.” (In an e-mail from the Eclipse set, Kristen effusively praises her costar, writing, “Dakota is one of the most consistently moving actors I have ever worked with. I’m always better with her.”)