Tierney: This is a no-brainer: Elle Fanning. With her innocent looks and sweet nature, she is the perfect choice to play little Primrose. Carina: The role was basically written for Fanning, but I'd go for an unknown here. Despite being a pivotal character, Prim is rarely actually involved in the action, so it's a small role for someone as established as Fanning. My pick is Sierra McCormick, who played the demon Lilith on "Supernatural." She's definitely got the look.