It’s tough balancing your life as a billionaire CEO and an armoured superhero – just ask Robert Downey Jr, who returns to the big screen this month in Iron Man 2. The close of the first movie saw his character revealing his identity to the entire world – so what happens now? Naturally the government puts pressure on Stark to hand over the armour he created, but there are other problems in the form of rival industrialist Justin Hammer (Sam Rockwell) and armoured villain Whiplash (Mickey Rourke). It’s time to call in the help of a few friends, so new characters include Russian superhero Black Widow (Scarlett Johansson), and Stark’s best pal Rhodey (Don Cheadle) getting his own armour to become War Machine. Sounds like Downey Jr will be taking things in his stride, then.

How did making this movie differ from the first one?
We broadened our cast and our horizons. The story is actually significantly more complex and subtle, but still you can follow it. It flew by, which was also odd.

What was the trickiest thing to work out story-wise?
Well, what does everybody best offer? All these insanely gifted people who have come to join us to play, how do we give them a real beginning, middle and end? How do we make them pertinent to a story that actually could have easily been told just continuing along the same lines we were, bringing in a non-descript bad guy and having lots of fighting. I think the trickiest part was living up to the ambition.

Where do we find Tony Stark this time around?
At a certain point, probably in act one or two, Tony is approached by Nick Fury [Samuel L Jackson], who is wondering what it’s like for him to not have any back-up. Then we see that he’s under pressure from the senate to essentially turn over the weapon that he designed when he was under contract to them. But the truth is that he didn’t design it for a government contract. He designed it to save his own life, so he has an argument there. Tony goes on a much more perilous journey this time than he did when all he had to do was save his own skin.

How did you guys approach bringing in the new people?
Well, I feel really beholden to say to people, ‘I promise you we will work hard to really pay this character off and give you what you would expect for coming to join us.’ I guess the problem, or the challenge this time, was that I was essentially saying that to three or four new people. Jon [Favreau, director] and I were telling Mickey [Rourke] that he wouldn’t just be playing a two dimensional nemesis. We were thrilled to get Scarlett [Johansson] and we said, ‘You’re not just going to be some kind of like B Marvel spin-off story thing just because we want a hot chick in this movie’ – and I think we managed that. With Sam [Rockwell], he’s just such a gifted guy that to come in, obviously it’s no secret now that he’s essentially filling the space Tony’s evacuated now that Tony’s said he’s not going to make weapons anymore; so what it is like to be a quote, unquote Tony Stark, and how does that add up to what his conflict is and all that stuff?

Don Cheadle has also joined the cast, taking over from Terence Howard as James Rhodes. Did you guys have to convince him to come onboard?
The thing is that Iron Man sold itself here two years ago, and then contrary to the number crunchers it wound up being a rousing success economically. So it was kind of a win-win situation. I think the convincing or rather the conversations really centred more around that it’s not uncommon to be sold a bill of goods and for one reason or another, usually not lack of intention, it doesn’t pay off. I’ve been in that position dozens of time. But we knew that as a creative collation we really tended to be able to make good on what we hoped to provide.

How will we see the characters develop in this movie?
For me this film is about Tony’s secret journey into his deepest fears, sense of obligation, his sense of legacy with his father, and his sense of brotherhood with Rhodey, and his ongoing deep love and respect for his assistant, Pepper [Gwyneth Paltrow].

Did your suit fit any easier this time?
Yeah, it was a little easier.

Is there a love triangle between Tony and Pepper and Tony and Black Widow?
I think we essentially started off saying love triangle. Then we realised that the love triangle is done in these superhero movies, and double love triangles, all the time. What we wanted was to do something just a little bit freakier than that, and I believe we have succeeded. Black Widow is a great character because she is not what she appears to be. It was a great opportunity. I don’t even know if it’s a love triangle as much as it’s Pepper is exactly what she appears to be. There is a lot more going on under the surface and that is brought to bear this time.

How surprised are you that Iron Man has changed people’s perceptions of you as an actor? You’re in a different place now than you were, say, three years ago.
Yeah. It’s pretty miraculous, but in a realm of miracles I think it’s probably a two or three, I guess. It’s a movie industry thing. Nonetheless, it’s mind-blowing to me. I had always felt like I wanted to and could do
something like this.

The plan is for you to eventually play Iron Man in The Avengers, which will see all of Marvel’s heroes coming together to form a team. Has the prospect of this sunk in for you?
Not entirely. I’m not as savvy about that stuff. I just know that right now we’ve got a really good thing going on and it’s important to not sully that. I’ll listen to the professionals and just keep selling soap until otherwise notified.
Iron Man 2 is released in cinemas at the end of this month.