Fincher comments on why he cast Pike in Gone Girl:
Rosamund was someone that I had seen in four or five different movies over 10 years, and I never got a bead on her. I never got a sense of who she was. And I pride myself on being able to watch actors and sort of know instinctively what their utility belt is, and I don’t have that with Rosamund. I didn’t know what she was building off of. There was an opacity there and it was interesting.