Twilight star Kristen Stewart has had enough of playing sweet and nice girl inthe series and now she is all geared up to play evil and darker roles in her upcoming projects. She likedplaying stronger roles in Snow White and the Huntsman and On the Road, which were very differentfrom the Bella Swan persona, and now she is all set to play a dark role of suicidal Peyton Loftis inher next film based on the novel Lie Down in Darkness, Aceshowbiz reported. In the novel, Loftis is apsychologically unstable girl who began to admire her own father. "I want to play Peyton more thananything I can possibly taste or touch in my life. I want to play her so bad. She's in love with him. I mean,I think she's in love with him. It's not his fault," Stewart said. The actress is also willing to play the darkcharacter of murderous Cathy Ames from the book East of Eden. "She is a troubled character who leavesher children to operate a brothel. She's a psychopathic, evil! I haven't done that yet."