Emma Donoghue, the writer of the best-selling book and the screenplay for Room, says that when the novel came out, every young actress in Hollywood wanted to play the part of Ma, the young kidnapping victim locked in a shed with her young son (including Rooney Mara, Mia Wasikowska, Emma Watson and Larson's close friend Shailene Woodley). But Donoghue recalls viewing the audition tape that Larson (who read the book in 2013, after her manager sent her a copy) had made in early 2014 and being blown away by the actress' sparkling conversation with an imaginary offscreen boy. "She conjured up that child," recalls Donoghue. "I really felt the child was there." She also cites Larson's commitment, how she lost 15 pounds to give herself the hollow, sinewy look of a longtime hostage. Donoghue remembers attending a lavish dinner with Larson and watching in astonishment as the actress ate the tomatoes off a piece of bruschetta, then put down the bread. "I know she was trying to stay very lean for the part, and I thought that showed an iron will," says Donoghue. "Who can put down the bread when they're eating the topping off a bruschetta?"
hollywoodreporter via pottershots