'Fault' Star Shailene Woodley Kisses Her 'Divergent' Brother and Tells

They play teens in love in the upcoming cancer tearjerker "The Fault in Our Stars." In this past spring's YA hit "Divergent," they played brother and sister, and they've got several more movies in that franchise lined up for the next few years.

There's no doubt young actors Shailene Woodley and Ansel Elgort — who appeared from New York in a live online question and answer webcast hosted by Yahoo Movies and Tumblr on Sunday — are spending a whole lot of quality time together.

But, as one reporter in the audience asked, was it awkward moving from playing onscreen siblings to romantic interests?

"I always wanted to know what it'd be like to kiss my brother," 22-year-old Woodley joked.

[Related: 'The Fault in Our Stars' Extended Trailer Brings the… Laughs?]

Then her serious answer followed: Playing 20-year-old Elgort's sister in "Divergent" gave both actors a jumpstart in developing their rapport for the delicate subject matter in "Fault."

"If Ansel and I hadn't known each other from 'Divergent,' our relationship in this movie wouldn't be what it is," Woodley said during the Q&A, "because we didn't have to go through the rehearsal phase of getting to know one another and getting comfortable with one another." 

Woodley also said that the familiarity between them helped open the lines of communication. "We were very honest with each other throughout the movies and throughout this process," she noted.

That became especially important when they didn't see eye-to-eye. "There'd be times when we'd disagree, and if we didn't know each other we might not say we disagree, because there's that politeness," Woodley explained. "We were very open with one another."

Woodley also expressed how she's looking forward to being siblings with Elgort again in the next three "Divergent" films (the final book, "Allegiant," will be split into two movies). She said, "And now we get to spend the next four years together, which is pretty freakin' rad."

[Related: 2014 Summer Movie Preview: Our 25 Most Anticipated Films]

When asked about their favorite scene in the film, based on the New York Times bestseller by John Green, most of Sunday's panel of cast and creators agreed: It's the love scene between Woodley, who plays Hazel, a girl suffering from spreading thyroid cancer, and Elgort's Augustus, a cancer survivor.

The love scene in "Fault" is very different than most love scenes in young adult films, argued Woodley, who believes teen love is just as, if not more, tender and real than adult love. "You look at adults and you're like, 'Are you actually happy? Is this real love? Because if that's real love that's not what I want.'"

"Teenagers are incredibly passionate," she continued, saying the scene stands out because Hazel and Augustus are "passionate with one another and a they're a little bit awkward and a little bit uncomfortable, but not too uncomfortable… I thought it was really special and unique."

As for Elgort, his favorite scene is a romantic one, as well — when Augustus tells Hazel he loves her for the first time in Amsterdam. "I really love the way that scene came out… It's so magical."

"The Fault in Our Stars" arrives in theaters on June 6.

Watch the full 'The Fault in Our Stars' cast and filmmaker Q&A: