Reporting by Josh Horowitz.

Though after "The Fault In Our Stars" opens tomorrow (June 6) Ansel Elgort and Shailene Woodley will be forever cemented in fans' minds as Augustus Waters and Hazel Grace Lancaster, the movie could have very easily ended up looking totally different. Nat Wolff, who plays Gus's blind BFF Isaac in the movie, actually did a full screen test and audition for the role of Gus.

Playing Isaac, he told MTV News, didn't even occur to him while he was auditioning.

"I hadn't really been thinking about that role, and once I got it, I was like, 'This is a deep role,' " he said.

To research the role, he met blind people to see how they acted and how they felt about not being able to see. In the end, he loved that Isaac was a funny character, "but there was an edge to him, to his reality."

"The Fault In Our Stars" hits theaters June 6.