In the April issue of Glamour UK magazine, Shailene also mentions TFIOS:
Tris’s brother is played by Ansel Elgort, who is also Shailene’s love interest in The Fault In Our Stars, an adaptation of the bestseller about two teens with cancer. “I read the book five times. I wrote emails saying I didn’t care if I was an actor in this movie or a PA, I just wanted to get it made,” she laughs. “When I fight for a role, I fight. I’m very determined.”
Read the whole transcript of the article here.
Thank you @Gossipgyal!