Mark Ruffalo attends the Chinese premiere of Avengers: Age of UltronWhen Marvel's "The Avengers" was released in 2012, one of the bigger question marks was: how was Mark Ruffalo, an actor known for his proclivity for esoteric indies, going to fare stepping into a giant franchise like this? (Especially since, we shouldn't forget, he was the third actor to inhabit the role in the past decade.) Of course, we all now know that Ruffalo, performing not only the human side of Bruce Banner but the motion capture role of The Hulk as well, would handily be the highlight of the entire movie, stealing every scene he was in and even generating an internet-sweeping meme centered around his bromance with Robert Downey Jr's Tony Stark.

In "Avengers: Age of Ultron," the ridiculously anticipated (and ridiculously wonderful) sequel, Ruffalo returns as both Bruce Banner and the Hulk and this time he does more than just brood and get really angry. That's right folks -- Bruce Banner is in love. And with Black Widow (Scarlett Johansson) no less! Oh, and he and Tony are also responsible for creating the malevolent robot Ultron (James Spader) who has grand plans to take over the world. But the Black Widow romance is probably more serious!

We got on the phone with Ruffalo to talked about all of these new developments in Banner's life, his new ownership of the character, working on the performance capture for the Hulk with a veteran of the technology, Andy Serkis (who pioneered its usage with characters like Gollum and Caesar), and what it was like when he tried his own Doritos flavor.

Moviefone: Bruce has so much more to do in this movie. What was your first reaction when you read the script?

Mark Ruffalo: I was thrilled. To be honest with you, I got to the part where you saw Banner really vulnerable. In the scene where Banner may or may not be embarking on another Avenger who may or may not be Black Widow but is definitely not a male Avenger, I was really moved by it to be honest with you. I thought, Wow, what a cool place to go in the middle of all this mayhem. And, of course, the Science Bros stuff was really satisfying and then I also knew that, technologically speaking, we had made a pretty significant advance in motion capture and facial motion capture that we were going to be able to do a lot more with Hulk. So I was really excited.

Did you lobby for any of this stuff?

I didn't do it while [Joss Whedon] was writing, but I did when we were doing the first "Avengers," I did say, "Wouldn't it be interesting to see Banner and Widow have something going on?" I was playing with that when we were doing the first one. I just thought those two characters had something that was kindred and something that would be really interesting to explore. So I laid that in there, almost half-jokingly. And then I am friends with Joss and I'd check in every now and again and I was shooting "Foxcatcher" and I was feeling particularly blue and I reached out to him and said, "How's it going? I haven't heard from you in a while." And he said, "Hey buddy, I just wrote one of my favorite scenes and it's you and Scarlett hooking up, having this forbidden love that could not be." And I just thought, Oh my god this is going to be great.

And you get to be one of the co-creators of Ultron!

Yeah, that's pretty cool.

You talked about the advancements in motion capture and there was talk of you and Serkis working together. What was that situation like?

Andy is on the frontier of this stuff and he, more than anyone, has developed it into a really performance-based tool. So he's got a really strong philosophy about that and has created a work environment that is really geared towards an actor creating a performance within that technology. And so we were working together on the physicality of it and also the attitude towards it -- that it is an extension of an actor's performance, that it is performance-driven and that there has to be a specific type of space created for that performance to happen in. He taught me an enormous amount about how to do that and how to insist upon it and how to work within it.

One of the big set pieces in the movie is the Hulkbuster fight. Did you do any of that?

Yeah, it was me with a stuntman that was about 7 foot 6. And so we did all of that. Sometimes it would be one or two stuntmen and it was with another stuntman. We did all that, all of those sequences.

Correct me if I'm wrong, but you seem to be embracing the character more this time around. With the first movie you seemed very happy to be invited, but now you're really taking ownership of the character. Is that the case?

I feel more comfortable in it and, especially with the motion capture stuff, that is something that we really haven't figured out completely yet. And it needs input and I had a lot of input before. But it is this interesting thing because you're working with this team of artists. It's a collaboration with the artists who are doing the CGI and so there's a dialogue going on there. As it develops, I really want to make sure it's as sacred a space and time as when the actors are rolling on any actor. So that's been an interesting journey to take with production and with myself and with the technicians as well. So yeah, we're creating it, and I do feel some sort of ownership in how it's coming along, because it's basically a completely new frontier.

Especially for you.

Especially for me! [Laughs]

Did Joss tell you where the Hulk is headed?

He's not going into space, although a lot of people think that he may be. He's definitely on his own and he's definitely heading far, far away from the Avengers. Nobody's talked about where, exactly. It's been an open question, I think because no one really knows what's coming next. We both love the idea that he jettisons himself away.

I know a lot of people dream about an action figure, but you get your own Doritos bag.


Your flavor is "Jacked 3D." What about you, what about the Hulk screams "Jacked 3D"?
[Laughs] I don't know what that is either! It's jalapeño flavored and I'll tell you, I had some yesterday. The bag itself weighs about seven pounds. And literally I had one and I drank a bottle of water and literally that one Dorito absorbed the entire bottle of water and then turned into cement in my stomach. Then it dried in my stomach.

"Avengers: Age of Ultron" opens everywhere May 1st.