Saoirse Ronan says a movie company is like a family doomed to break up.
"I've never been able to fully accept after a movie or TV show that it will be a year before you see these people again at the premiere," the Oscar-nominated 15-year-old actress said. "And you're never actually going to be with this whole group of people again, ever. After spending long hours together for weeks or months, it's a hard thing to deal with."
But something wonderful happened when Ronan was making "The Lovely Bones."
The Irish Ronan and New Zealand actress Rose McIver, who plays her big sister in the film, hit it off so well on the set that they've been able to forge an enduring friendship.
"It's funny," Ronan said in a joint interview with McIver. "Rose and I don't have all that many scenes together. But even on days when she wasn't working she showed up on the set, and we got to know each other very well."
"Neither of us has a sister,"
the 22-year-old McIver said. "So that's how I think of us. Saoirse is like my sister - my big sister. I'm six years older, but she's an old soul."
"Yeah, I am an old soul," Ronan confirmed.
"It's natural because she's spent so much time around adults. I met her when she just turned 13, and she certainly didn't come across as a 13-year-old," McIver added.
Despite the grim subject matter of "The Lovely Bones" (a murdered girl watches from the afterlife as her family copes with the tragedy), the set was remarkably happy, Ronan said.
"I can't think of one day when I didn't want to go in and work," she said.
Acting careers can be hard on young performers, who often spend their adolescence in front of a camera instead of going to school and hanging with friends. That makes the relationships they forge on the job all the more important.
"I remember my first TV show," Ronan said. "I was only in it for two weeks, but I was so upset when it was finished. You're around intelligent, clever, creative people who are as passionate about a project as you are. Breaking away from that is tough."
"Plus," McIver said, "when you spend long hours away from home among other people, you get a real sense of intimacy. Saoirse and I have kept in contact since we completed 'Lovely Bones,' which I think is sort of unusual."
"Very," Ronan added. "During a job, there are an awful lot of people you meet and like and genuinely want to keep in touch with. But in reality, you don't keep in touch with many of them."
McIver has often worked in films and TV shows shot in her hometown of Auckland, which allowed her to stay in touch with the people she grew up with, but Ronan hasn't worked in Ireland much.
McIver finished high school and doesn't feel she missed any of the usual experiences, but Ronan said the celebrity that came with the film "Atonement" and her Oscar nomination made school impossible.
"I have to be home-schooled, because I attract too much attention if I attend regular classes," she said. "That's the only time I feel I'm missing a part of normal growing up. But even then, having a one-on-one relationship with my tutor has been really satisfying.
"And the opportunities, the experiences, the people I've met - I wouldn't give that up for anything."