Most moviegoers wouldn't expect to see indie darling Scarlett Johansson in an expected blockbuster such as "Iron Man 2," but she's hardly avoided the chance to cash in on her fame.  Then again, most of those studios choices including "The Nanny Diaries," "The Other Boleyn Girl" and "The Black Dahlia" have hardly been the hits she expected them to be.  To say her new role as comic fan favorite the Black Widow in the "Iron Man" sequel is a slam dunk is something of a complete and utter understatement.  At least in the hit department.

Speaking at a press conference with her co-stars in Los Angeles on Friday, Johansson elaborated on why she decided to take the supporting role to Robert Downey, jr.'s improv antics as the armor-clad superhero.

"Well, I've never really seen this kind of film, a film of this genre where the female characters, that their sex appeal came second. I mean of course they're sexy characters and you have a sexy secretary or a girl swinging around by her ankles in a cat suit, that's innately sexy." Johansson says. "But the fact is that these characters are intelligent, are ambitious, motivated and calculated to some degree."

And then making it clear she wouldn't have signed on board for just any guaranteed paycheck, Johansson adds, "To be just a pawn in this story of a whole bunch of men fighting it out and rolling around and getting down and dirty and there you are to be the sort of vision in a tight cat-suit would be a boring thing to me."

Johansson is first introduced as Natalie, a potential new assistant for Stark. It's no secret though that the Widow actually turns out to be an agent of the super spy organization SHIELD.  Nick Fury (Samuel L. Jackson) has her infiltrate Stark's world so he can keep an eye on the increasingly out of control playboy.  Widow, whose real name is Natasha Romanoff (although she's somehow lost her Russian accent in the jump to the big screen), becomes a key component of Stark's tussle with the revenge seeking Whiplash (Mickey Rourke) and his benefactor, rival industrialist Justin Hammer (Sam Rockwell).

Like many twentysomething actresses in Hollywood, Johansson had numerous meetings with Marvel Studios about landing a role in their ever-increasing big screen universe, but says it was director Jon Favreau's vision which sealed the deal.

"I think that Jon really made that very clear in the beginning, that he felt as far as Black Widow was concerned that she was mysterious and nuanced and something to kind of peel back the layers to," Johansson says. "I think that's why this film is so much more dynamic for me as an audience member."

In fact, Johansson admits she's never been a fan of this sort of flick, but viewed both her and co-star Gwyneth Paltrow's character of Stark confidante Pepper Potts as the "brains" behind the operation.  Johansson reveals, "It's oddly kind of old fashioned actually in the best sense of the word. These characters are like those fabulous femme fatales of the kind of golden age of Hollywood, that Bette Davis more than the Jane Mansfield which I think is so much more dynamic to watch."

Johansson may not be entirely comfortable in the "Iron Man" world, but won't be able to escape its trappings for long though.  Her husband, Ryan Reynolds, is currently shooting the DC Comics adaptation of "Green Lantern" and is also expected to reprise his role form "X-Men Origins: Wolverine" in a solo "Deadpool" film.  As for Black Widow getting her own picture, Marvel Studios head Kevin Feige says it's "definitely possible" but most true believers expect her to at least cameo in the ensemble "Avengers" franchise.

And while the 25-year-old actress has a tendency to be overly serious about her work, she did display some good humor about playing the Widow. When a journalist asked what the different would be if the acclaimed actresses were the film's main heroes, Paltrow replies, "If Scarlett and I were doing it the body count would be different, less bloody."

And as deadpan as possible, Johansson adds, "More organized. We'd just stack them."

"Iron Man 2" opens nationwide and in IMAX on May 7.