Dakota Fanning's sister Elle has "picked her up" when she's "fallen apart".
The two famous siblings have their own production company, Lewellen Pictures, together, and while they are "different personality-wise", that's what helps them support each other so well.
She told The Cut magazine: "She has her emotions on her sleeve, and people would say she’s a free spirit. I’m more of that stereotype of the older one who keeps everything together and is pragmatic.
"But the dynamics shift as you get older — there have been times when I’ve fallen apart and been wild and she’s picked me up.
"When it comes to the company, we’re super in sync and usually pretty much have the same opinions on things.
"There are things that we work on together and then there are things that she does or things that I do, and it all just kind of is instinctual."
Dakota, 30, and her 26-year-old sister are currently working on an adaptation of Paris Hilton's memoir after buying the exclusive rights for a collaboration between them, A24 and Paris herself.
The 'Twilight' star added: "This is my girlhood dream come true; it’s such an exploration of the early 2000s. Paris is a friend now, which is like, if you told me this at 12, I would’ve lost my s***.
"She’s a genius. She knows exactly what’s going on. Nobody’s been fooling her. She’s dealt with super-traumatic situations in her life."
At a recent party celebrating the socialite and singer's new album, Dakota posed for a cheeky photo with stickers on her chest with Paris' "that's hot" catchphrase on them.
She reflected: "Maybe I wouldn’t have put 'that’s hot' stickers on my chest and posted a picture of it a few years ago, but here I am. That’s me!
"And it’s always been me. Who cares, why not? It’s like my favorite picture of myself.
"My sister and I are both excited about it and getting to know Paris in a very real way. It’s so wild because we grew up in her heyday — which, I mean, has she ever really not had a heyday?"