Scarlett Johansson is the Black Widow in 'Iron Man 2'

Johansson plays the Black Widow, who in the comics is a Russian spy-turned-superhero who fights crime in a skintight catsuit. Johansson said she knew from seeing the character and production sketches that she’d be in something that fit her form.

“So I had a freak-out moment, but then it only lasted about a half a day and then it’s like, ‘Suck it up,’” she said while promoting the film at Comic-Con. “You’ve got to just do it and so I never turned back after that. I just went, like, full force and did it.”

“Iron Man 2” is the sequel to the highly successful 2008 film “Iron Man,” which starred Robert Downey Jr. as weapons manufacturer Tony Stark. When Stark is kidnapped, he’s forced to create a suit of armor to escape — and to keep his injured heart beating.

Johansson is an addition for the sequel as Natasha Romanoff, aka the Black Widow.

“We don’t know necessarily whether the character is villainous,” she said. “She does have a dark past, and I think that she is very seductive and distracting and we are ... not sure exactly where she's coming from and what her intentions are necessarily.”

Johansson said the Black Widow uses a smorgasbord of fighting styles, all of which needed to work in conjunction with the costume.

“One thing obviously important for my character is that the costume moves,” she said. “You know the character is an expert of hand-to-hand combat. She’s a mixed martial artist. She comes from a dance background. There’s some, like, gymnastics thrown in. It’s kind of everything all thrown into one big sort of fighting machine, so a big part of me is, like, ‘Can I move in this? Can I run in it?’”

She said ultimately, intensive training and repetition prevailed.

“You just have to put in the hours,” she said. “That’s what I realized, is that just putting in the hours and doing the training and repetition and basically just befriending the stunt team and spending all day, every day, just over and over and over and over until you sell it.”

Johansson said the Black Widow character remains mysterious in “Iron Man 2.”

“This movie is not about revealing the Black Widow identity,” Johansson said. “Hopefully if the character continues on, whether that be through ‘Avengers’ or something like that, we’ll be able to explore more of her past.”

“The Avengers” is the big Marvel movie that is planned to join the stars of the Marvel Comics films “Iron Man,” “Thor” and “The First Avenger: Captain America” together. Joss Whedon (“Serenity”) was recently reported to be in final negotiations to direct that film.

Johansson is signed on for multiple Marvel films, and could become part of the “Avengers” team.

“I didn't go into this going ‘Oh this is the last I ever want to see this character,’” she said. “I would love to see the character come back and, as I was saying, kind of reveal more about herself.”

She said usually actors in a film just have one shot to connect with the audiences as a character over a two-hour segment.

“So for me to be able to bring something like this back and kind of develop the character is exciting,” she said. “And something that we don’t normally have the opportunity to do as actors.”

Johansson said that even though new characters have been added for “Iron Man 2” — including her Black Widow, Sam Rockwell’s Justin Hammer and Mickey Rourke’s Whiplash — she felt like it all balanced out well in the end.

“I think the fans will be really excited to kind of be taken on all these different journeys,” she said. “They all really play into one another and it doesn't feel like a lot of different films coming together. It really feels like an ensemble.”