updated 08/28/2014 AT 4:05 PM ET
•originally published 08/29/2014 AT 1:20 PM ET
“She reveals a lot about the female experience, both positive and negative,” Pike, who plays Amy opposite on-screen husband Ben Affleck in the upcoming film adaption, tells PEOPLE. “It’s why people are shocked by her, seduced by her.
“She reads you better than you read yourself,” Pike, 35, notes. “That can be incredibly powerful and incredibly alluring.”
It can also be hard to shake, as Pike found after stepping into the role for several months in the film directed by David Fincher and written by Flynn.
“It took a while to fully come back to myself,” says the former Bond girl, who is expecting her second child with partner Robie Uniacke. “I went on holiday, but it wasn’t really until after that that I felt I was divesting myself of Amy.”
The massive anticipation surrounding the film, which hits theaters Oct. 3, “feels like a ship in a storm,” says Pike. “If I can pour a bit of Amy’s resolve, her careful, meticulous brain would be quite useful. But I’m not sure it would be that good for my other half.”
As for Flynn, she admits that writing a novel about a curdled marriage while still a newlywed herself might strike some as a little strange.
“I joke about my husband being the muse for the most toxic marriage in the world,” the mom of two tells PEOPLE, “because if I’d been married to a less secure man, it wouldn’t have gotten written. He said to me over and over, ‘Write it, don’t censor yourself, don’t think about the outside world and we’ll figure out the rest later.’ He was very responsible for this awful book about marriage!”
For more with Rosamund Pike, Gillian Flynn and additional interviews with the stars of fall’s hottest movies, pick up this week’s issue of PEOPLE, on newsstands Friday