Robert Downey Jr., Jon Favreau for “Iron Man 2”

Early in the press conference for ‘Iron Man 2,’ Robert Downey, Jr. is asked whether there’s any truth to a rumor he’ll be playing the vampire Lestat in an adaptation of Anne Rice’s novel of the same name. Downey leans forward and squints through sunglasses, looking back at the reporter as if he honestly can’t remember whether he’s meant to play Lestat or not. Then as only he can without sounding like an unbelievable asshole, Downey responds deadpan, ” Anything that’s going on, just imagine it’s been offered to me.”

With his talent for whip-fast free-association, and his unapologetic just-kidding-but-not-really arrogance, Robert Downey, Jr. can be difficult to separate from Tony Stark, his character in ‘Iron Man,’ and that, in large part, is the pleasure of the franchise: the unique stamp Downey has put on his lead role. Off the strength of the first film, Downey’s career was powerfully re-launched, and in the time between originating and returning to his breakthrough role as a billionaire superhero, Downey has become something of a billionaire superhero himself.

But star-wattage aside, the challenges of building a worthy sequel are not to be underestimated. ” (It’s like) throwing a party and you don’t know if people are going to show up,” says director Jon Favreau, comparing the making this sequel to that of the first film. ” Here, we knew people were going to show up and we wanted to make sure everybody had a good time.” The original ‘Iron Man’ earned high marks from critics and audiences for its light tone and humor, as much as for its action. Duplicating box office success likely won’t be hard, with fans primed for the 2010 summer season’s first big franchise installment… But profitability and quality are often separate matters.

‘Iron Man 2,’ picks up six months after the end of ‘Iron Man,’ with Ivan Vanko (Mickey Rourke,) a Russian ex-con, plotting his revenge against Tony Stark – and building his own variation on the Iron Man suit to mount his challenge. Vanko becomes Whiplash, who is a very different character, at least on the surface, than his pen-and-ink antecedent. ” Whiplash in the comic book is a guy wearing tights with a big plume, a big purple feather coming out of the top his head,” says Favreau. ” That wasn’t what we wanted. But, (we asked,) what’s the tech version of that?” The design that ultimately made it into the film was inspired, Favreau adds, not only by an overall ‘dirty tech’ look, but specifically by David Cronenberg’s ‘Eastern Promises,’ and its protagonist Nikolai (Viggo Mortensen,) a chiseled Russian, covered, as is Vanko, with prison tattoos.

Mickey Rourke, who plays Whiplash, was brought into the ‘Iron Man’ fold through the lobbying not only of Favreau and producers, but of Downey, who found himself alongside Rourke frequently on the 2009 awards circuit, when Downey was frequently nominated for his work in ‘Tropic Thunder,’ and Rourke for his own career re-launch, Darren Aronofsky’s ‘The Wrestler.’ ” I really worked you like a rib, didn’t I? Begging you in public,” Downey remarks across the table to a recently-awoken Rourke, who says the atmosphere on-set was a collegial one, from which made at least one great friend: Whiplash’s signature cockatoo in the film inspired Rourke, an animal lover, to buy a tropical bird of his own. He named it Elvis.

Whiplash’s counterpart in ‘Iron Man 2′ is unscrupulous industrialist Justin Hammer, played with gusto by Sam Rockwell, who was once up for the role of Stark himself. Originally, Favreau says, Rockwell and Rourke’s characters were one – but in later drafts, were divided into two: the brutal Whiplash, and smarmy Hammer. Still, Favreau was well aware of the stumbling blocks of many previous superhero sequels. ” The trick is to feather (villains) in, so they don’t overwhelm the story and you don’t suffer from villainitis,” he says. ” By having Justin Hammer and Mickey Rourke’s character come together fairly early, you really have two storylines that are weaving. You don’t have five separate storylines… We really tried to keep narrative flows going so it didn’t get too convoluted, ’cause I lose track of that stuff. Especially in sequels as franchises get more complex, I don’t always remember what happened in the last movie. Not for nothing, I like watching stuff blow up, but I don’t want to do homework before I see a sequel.”

Soon, however, homework may be exactly what the average viewer will have to do, with ‘Iron Man 2’ representing just one star in the ever-expanding universe of Marvel movies (such as Kenneth Branagh’s ‘Thor’ and Joe Johnston’s ‘Captain America,’) all of which are – at least in theory – meant to be linked to one another for ultimate payoff in the Greatest Marvel Superhero Story Ever Told, Joss Whedon’s ‘The Avengers.’ To that end, Samuel L. Jackson and Scarlett Johansson appear in ‘Iron Man 2’ as Nick Fury and Natasha Romanoff, agents of S.H.I.E.L.D., though Favreau insisted their inclusion not detract from, or cheapen, the story of Tony Stark himself… Kevin Feige, President of Marvel Pictures, notes that on the cluttered timeline of the Marvel motion picture universe, ‘Iron Man 2’ takes place before 2008’s ‘The Incredible Hulk’ starring Edward Norton. And for those willing to sit through the end credits of ‘Iron Man 2,’ there’s a revelatory ” easter egg” that clarifies matters. No word yet on whether it will be on the quiz.

In the role of Tony Stark’s friend James ” Rhodey” Rhodes, Don Cheadle stepped in to replace actor Terence Howard, and despite speculation that this might have made for contention between Cheadle and Howard, Cheadle said there was no bad blood: ” Terence is a friend… We’re cool.” Still, Cheadle undeniably gets to do more in the role of Rhodey than Howard did, notably, in wearing the ‘War Machine’ armor suit designed by Justin Hammer. ” I don’t know why my suit was heavy metal while (Robert’s) was made of a light fiber-glass,” he says. ” Maybe it was an initiation.”

Returning in the role of Tony’s assistant/confidante Pepper Potts is Oscar-winner Gwyneth Paltrow. Pepper and Tony’s ‘will-they-or-won’t-they’ dynamic is paid off in the sequel with the inevitable smooch. ” It was great,” she says of shooting that scene, ” Because both my husband and his wife were right there.” Downey interjects: ” She said to me that I didn’t know what I was doing, it didn’t feel good… Despite what she said on set, she still thinks about it.” But sexuality isn’t all there is to Pepper Potts, says Paltrow, and that’s part of what sets the ‘Iron Man’ franchise apart: ” I think it’s a very smart decision to have women who are capable and intelligent, because it appeals to women, so it’s not only a film for fifteen year old boys, it’s a film that relate to a lot of people on a lot of levels… ” For her part, Johansson adds, ” I think fifteen year old boys will like it too.”

And, they likely will. Superhero films, after all, are based in adolescent wish fulfilment, a time-tested font of revenue. When Downey is asked if he himself ever had his own such fantasies, and dressed up as a comic book hero as a kid, he responds, ” Growing up, no, but in my mid-thirties in Palm Springs right before an arrest, yes.” He may have started late, but today, Robert Downey, Jr. seems to have no problem playing the part of super-star.