In the cancer dramedy "50/50" and the broken-marriage tale "Take This Waltz," he delivers moving, nuanced performances that have many cinephiles wondering if he's now headed in a more dramatic direction.
But the actor-writer - whose credits include the smash comedies "Pineapple Express," Superbad" and "Knocked Up" - insists that's not the case.
"It was never something that I consciously did, nor is it something that I consciously want to continue doing, honestly. They just happened to come back-to-back," Rogen, 29, said in an interview at the festival.
"With '50/50,' it was about something very personal that our good friend went through, and so with that it just felt like we had to make a movie because we had lived it. And with 'Take This Waltz,' it was more just Sarah (Polley's) unexplainable desire to have me in her movie that is what made me do it, honestly."
"No part of me ever thought I would do a movie with a tone like 'Take This Waltz,' but she really seemed to think that I was right for it and she's smart so I thought: 'Eh, maybe she's right,'" he said with his trademark yuk.
In "50/50," set to hit theatres Sept. 30, Rogen plays the joker best friend to Adam (Joseph Gordon-Levitt), who learns he has a rare and possibly fatal form of cancer. Rogen still delivers his amiable, slacker brand of comedy in the role, but also displays a sweet sincerity.
Anna Kendrick co-stars as Adam's fledgling therapist; Bryce Dallas Howard plays his insensitive girlfriend; and Anjelica Huston fills out the role of his doting mom.
The story is inspired by the experience of Will Reiser, who's long been friends with Rogen and his writing-producing partner, Evan Goldberg. The three met when they were in their early 20s on the set of the British comedy series "Da Ali G Show," where Rogen and Goldberg were writers (they got an Emmy Award nomination for their work on the program) and Reiser was an associate producer.
Eight months after they wrapped on the show, where they were the youngest staff members, Reiser revealed he'd been diagnosed with cancer.
On the encouragement of Rogen and Goldberg, he wrote a screenplay loosely based on what he went through. Eventually, Jonathan Levine jumped onboard to direct while Rogen, Goldberg and Ben Karlin ("The Daily Show with Jon Stewart" and "The Colbert Report") produced.
"To me, there's a school of thought that says the less comedic an idea inherently is, the more creatively ambitious it is to try to make it comedic, I guess, especially without sacrificing the integrity of the subject matter," said Rogen, who has written and/or produced several films with Goldberg.
"A lot of our movies, this one probably more than the other ones, on paper could be very dramatic. 'Superbad' could be a dramatic movie, you know - a movie about high school guys who can't have sex and are going to be alone in college. I mean, you could make a dramatic movie about that, if you really wanted.
"But to us, it seems like people's fears and the bad things in people's lives deserve as much comedic attention as the good things in people's lives, I guess."
For "Take This Waltz," Rogen brings a vulnerability to the part of a cook whose writer-wife (Michelle Williams) pines after their neighbour (Luke Kirby).
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