But it's a pretty big departure for the pair who just recently co-starred as brother and sister in the sci-fi flick Divergent.
So what's it like for them to cuddle up onscreen so soon after playing siblings?
"It's so much fun, cause I've always wanted to make out with my brother," Woodley jokingly told E! News at the junket for Fault.
On a more serious note, Woodley, 22, admitted she was surprised Elgort, 20, got the part.
Christopher Polk/Getty Images for MTV
"I actually didn't think at first that he would get it, or that even if he was good, that he wouldn't get it, because of our relationship in Divergent," Woodley admitted.
But when the pair did a screen test together, Elgort blew the casting team way.
"Everybody in the room was sort of like 'wow,'" a very proud Woodley gushed.
Based on the acclaimed novel by John Green, the movie tells the story of two teens who fall in love after meeting at a cancer support group.
The Fault in Our Stars hits theaters June 6.