'Bel Ami' Features Robert Pattinson Nude A Lot, Says Co-Star (VIDEO)

Robert Pattinson shows his dark side in an upcoming film, and that has nothing to do with being a vampire.

The "Twilight" star, who will feature in April's "Water for Elephants" alongside Reese Witherspoon, will also star in "Bel Ami," about a young man who uses his sexual prowess to work his way up the ladder through the prominent socialite women of 19th century France.

Natalie Tena, who plays one of those women, spoke with MTV about what the revealing film.

"There is a lot of everything in that," she said, speaking of nude body parts. "But the thing is, I knew him before all the 'Twilight' stuff. We used to hang out for a bit, so it was a bit weird [filming sex scenes]. I was like, 'All right, mate, come on, let's do it! It will be fun!'"

While Pattinson will do some tasteful, PG-13 sex scenes in the upcoming "Breaking Dawn," his frequent "Bel Ami" beddings are causing some problems with the film's marketing team.

"We were really true to the book and because the guy is basically a s**t who wins everything at the end it's really difficult to market it - especially with me in it," Pattinson told Total Film last week. "Everyone's worried that everyone's going to be thinking, 'Oh I want him to be nice, he's got to be nice to all the ladies.'"

Along with Tena, Pattinson's "Bel Ami" lady co-stars include Uma Thurman, Kristen Scott Thomas and Christina Ricci, who this winter raved about Pattinson's kissing skills.