EXCLUSIVE: Evan Rachel Wood Opens Up About Motherhood, Friendship With 'Into the Forest' Co-Star Ellen Page

'He's the best thing to happen to me,' Wood said of her 3-year-old son.

Evan Rachel Wood has found a "sister" in Ellen Page.

The two star together as sisters trying to survive an apocalyptic world in Into the Forest -- and while they became fast friends on set, it seems they've admired each other for quite a while.

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"She's somebody who I've wanted to work with for so long and I've always admired her work," Wood told ET's Denny Directo on Wednesday. "One of the things I loved about this film is that you usually don't get to work with your peers -- you're sort of always competing for the same roles. But Ellen was always one of those people where I was like, 'Well, if it's not me, I'm glad it's her!'"

Page -- who also produced the film -- was also a fan of Wood before they met, noting that she admired her work in Thirteen and Pretty Persuasion. "I had wanted to work with Evan for a really long time," Page revealed. "I asked her to do the movie and then we sort of became friends in the course of getting ready. Getting to work with Evan and do something so intimate and play sisters with each other, that was really incredible."

"We have very similar senses of humor," Wood added, explaining how the two became such close friends. "The film was so heavy and we would have these crazy emotional days. At the end of the night [to] come back to the apartments we were staying at, our rooms were right next to each other, it was like being sisters," she said.

"It was like being a kid. We'd just watch Family Guy and giggle all night, and just make the dumbest jokes," she elaborated. "That was the most surprising, how we could slip into this child-like, sister vibe."

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The 28-year-old actress had a lot to say about family, also opening up about motherhood and raising her young son. Wood, who has yet to release the name of the 3-year-old she shares with ex Jamie Bell, is clearly protective of her little one.

"Doing a film like this, [I] think about what the world is going to be like for [my son] and his children. And there is a real part of me that wants to take him out for survival courses and things…because you just never know," she said.

"It's less about me," Wood continued, on how motherhood has changed her. "You become less self-obsessed and you let go of things. You forgive your parents for stuff, and you’re more at peace and you'e more motivated."

"You know you have to be an example for this child, so you have to be the best person. You can't just say, 'Do as I say, not as I do,'" she elaborated. "He's the best thing to happen to me, for sure."

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Page recently became a mother herself, to an adorable new puppy last October.

See the cute pup she adopted with girlfriend Samantha Thomas in the video below.