As Shailene Woodley tells it, casting the role of "Four" in Summit's upcoming YA adaptation "Divergent" was no easy task - simply because none of the young actors who came in could achieve the correct balance needed for the part.

"We had read every single young man out there between the ages of I would say 16 and 30," Woodley told us while doing press for the movie at San Diego Comic-Con. "And nobody really had the essence of being vulnerable and masculine at the same time. Some guys came in and were so incredibly masculine that there was no depth there, there was no sensitivity, there was no vulnerability. And then...I'd say 98 percent of the guys came in there and I was tougher than they were. They were just not very masculine. And so it was really, really difficult to find somebody."

Imagine her relief, then, when "Bedlam" star Theo James came in to read for the part - and nailed it.

"After the audition, he kinda left and everybody looked at each other and were like, 'holy shit, that's him,'" she continued. "Like, 'we just spent four months looking for Theo James.'"

James, meanwhile, told me he felt an "affinity" not only for the character (the love interest of Woodley's tough-minded heroine Tris Prior) but for Woodley herself.

"It just felt very right," he told me. "Me and Shai had a very natural rapport, a natural chemistry. So it was something that seemed just...you know, it just seemed to kind of slot, which is really nice, it's really great and gratifying, because then...there's no questions of, 'how exactly is this gonna fit?'"

Not present during the interview was Woodley and James' Oscar-winning co-star Kate Winslet, who plays the role of villainous Erudite leader Jeanine Matthews in the film. When I asked what it was like to work with the actress, Woodley responded by relating Winslet's displeasure with the size of her trailer upon her arrival on-set - though not for the reason you might think.



"Kate was mortified that she had a bigger trailer than us," said Woodley. "She's like, 'I just noticed that I have a trailer that's bigger than all of yours. I feel mortified. I can't believe they did this.' Because she's so down to earth and she's so humble that that was a really big deal to her."

To check out the full interview with Woodley and James, click on the video above.

"Divergent" is slated for release on March 21, 2014.