Natalie Portman and Barbara Hershey became penpals as they were making new movie BLACK SWAN - because they couldn't be on set together.
The two stars play mother and daughter in the film but had no time to bond before shooting started, so director Darren Aronofsky suggested the two actresses write to each other.
Portman says, "Darren did a really beautiful thing where he had Barbara write letters to me in character as Erica to Nina for the first portion of the film. He'd hand them to me during important days of shooting that I should feel my mother.
"Barbara wrote really, really gorgeous letters."
Hershey adds, "It was an amazing idea because I couldn't be around and she was in the midst of filming and I was in Europe, so it was a chance to feel each other's characters and it came out of me without any thought.
"The letters were very easy to write which really shocked me. It gave me the door to my character which was great."