Paul Bettany's vision for The Vision is coming a little more into focus.

The actor, who plays both the voice of Tony Stark's A.I. valet J.A.R.V.I.S and also the synthezoid superhero -- who may be one and the same -- hit San Diego Comic-Con International to join his "Avengers: Age of Ultron" co-stars on stage for the big Marvel Studios presentation -- but earlier in the day, he joined a select group of reporters for an intimate roundtable conversation about his still enigmatic new role in the Marvel Cinematic Universe.

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Even before the questioning started, Bettany made it clear how tricky his answers were going to be as he tried to stay spoiler-protective. He made a quick check out the adjacent hotel window to gauge his safety. "Let me just look up -- oh, okay. I can't say anything!" he joked, pretending to spot a sniper. "I don't like sitting near an open window with my back just in case there's a Marvel [sharpshooter]. I can see light glistening off a telescopic lens."

Did you always have in your contract '"Hey, if these movies do well, I want a better role where I can actually play an actual superhero?"

Paul Bettany: [Joking] Yes.

No, I didn't. And for a long while, actually, I discovered that having played J.A.R.V.I.S. in the Marvel rulebook, I wasn't allowed to then play another character. And ["Avengers: Age of Ultron director] Joss Whedon and I got on very well, and he looked for a way to make that happen. And he found one, so I'm very happy.

What is the relationship between J.A.R.V.I.S. and The Vision?

Can't tell you. I can tell you there is one. I'm supposed to keep it vague and mysterious, which I will do. Everything's a double-edged sword, right? I used to turn up for 45 minutes in a darkened studio and be J.A.R.V.I.S. for 45 minutes, and then they'd give me a huge bag of cash, and I would go about my way like a burglar with swag and a striped thing. Like, 'Can this be real?' And now, they want me to work for my money [Laughs], which is great and sweaty and hot. Bearing in mind, which you'll realize once they unveil everything, it's a very sweaty and hot decision that got made, but it's really fucking cool. It's really cool, and it's just been a ball to sort of join this train that is on really clear tracks and really lovely, funny, creative people. It's been a joy, really.

What interested you about The Vision when you heard about the character and got a chance to look at the history?

Well, I've got to say that the greatest thing about this job for me is that however much research I could do, I would never know as much about Vision and the world as [Marvel Studios head] Kevin Feige and Joss Whedon. So it's really nice to sort of acquiesce all responsibility of that to those guys. The thing that appealed to me was this sort of nascent creature being born and being both sort of omnipotent and totally naïve. And the danger of that and the sort of complex nature of somebody, of a thing being born that is that powerful and that fully created in a second. And the choices that he makes morally, I think, are really complex and interesting. They've really managed to maintain all of that. The bit I love, the famous image of him crying is, I think, really expressed kind of beautifully in this Avengers.

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From a working perspective, this seems like it might be an amazing ensemble cast experience. Was that how it worked out for you, or are you working primarily with one or two people?

That's both those things. I mean, initially, it was everybody on set at the same time, and it was the sort of introduction of Vision on the first day. And that was huge, and everybody was incredibly welcoming, and really prepared. Now, that sounds really stupid, but I can't tell you the amount of times you turn up on a set with huge, famous, overpaid actors, and they haven't done any work. You're going through the scene, and you realize, 'You don't know what the scene is!' And that happens more often than is noble. But this situation, there's so many characters to cover, for a filmmaker, that everybody's getting two or three takes. So everybody's really on point and really focused and really creative. And just in a really lovely atmosphere. It's been great.

Can you talk about finding the voice for the Vision versus J.A.R.V.I.S.?

I can't really. I mean, not for any other reason than it happens entirely naturally as you're on set, and that those things are hard to analyze. And there are absolute differences, clearly.

So it wasn't something that you really worked on beforehand? You just came to set?

Well, I worked on it, but then the interaction between other people, other actors, changes things. And your interaction with the director changes things. But he is not J.A.R.V.I.S., and he is not a child of Ultron. He is The Vision. And that weirdly happened on its own.

After four films together, did you finally get a chance to work directly with Robert Downey, Jr.?

Yeah, it was lovely. And because oftentimes, we'll say these quite outlandish things to each other on these sorts of movies. And with all of them, with him and with [James] Spader and [Mark] Ruffalo and [Chris] Hemsworth. And it's amazing how you can sell these very outlandish notions, farfetched ideas.

What is Vision's relationship with Stark like?

Um... well, I think that Vision probably feels paternal towards a number of people.

How many of those guys do you get to punch?

I'm really good at punching. Vision is very good at punching.

What's Vision's relationship like with Elizabeth Olsen's Scarlet Witch?

[Long pause] Protective.

How many movies does Marvel want to see you play the Vision in?

368.

Lot of bags of cash.

Lot of bags of cash. It's good for the family business.

We heard yesterday that there's a more traditional -- to the comics -- version of Edwin Jarvis coming to the television series "Agent Carter." Did they fill you in how that relates to your J.A.R.V.I.S.?

No, no.

J.A.R.V.I.S. is a fairly sassy character, and I assume the way you're describing Vision, that's not going to be the same for him. Did you miss that in the shift to Vision, or was there some other element of him as a character that you enjoyed playing?

I wouldn't say I missed it because I don't think that it entirely went away. You'll see. And as he is born and becomes more realized, it's hard to be ironic when you're -- I know what you're talking about because there's a sort of irony and knowing with J.A.R.V.I.S., but it's hard to be -- I mean, babies aren't particularly ironic. But he's somebody who is learning about the world at quite an exponential rate, and he becomes more sassy as the movie continues.

How do the rest of the Avengers feel having Vision around?

Incredibly jealous! [Laughs] It's just been, like I said, a really lovely working experience. I think there's a lot of, initially in the plot, as it were, a lot of distrust, and that has to be navigated by The Vision, and he does it in a quite extraordinarily shocking way. He gains their trust in a real -- it will be -- it's a real roof-raiser of a moment. Everybody will flip.

Are you Vision when the story starts or is this later?

It is -- you might have gone to get your popcorn by the time you get your -- yes. Minutes have passed. I don't know how many.

Do you get a wear a yellow cape?

Can't discuss that! There is a cape, and it's fabulous!

How does it feel putting on the costume? You look in the mirror, get to the set -- how do people respond to you?

With a great deal of pity. It's a real thing, and we spent a lot of time working on how to keep me cool in that costume because that costume is, whilst one of the most genuinely, in all of the work I've ever done, just an extraordinary achievement, has nothing to do with me. It's just a really beautiful piece of design. And then manufacturing this thing out of a lot of materials that haven't existed for a very long time. It's really cool looking. The consequence is that it's fucking hot!

Can you talk your approach to playing a character that goes through such a rapid evolution?

Yeah, I talked a lot about it with Joss, and it's sort of about experiencing and processing things in the moment and super humanly quickly is really the -- I know how that feels to sort of play it. But it will be up to other people to judge whether that has been realized, is this sort of, 'Wow -- so that's really happening.' And the whole time people asking me questions, and really genuinely working out the question in the moment rather than having a pat answer to questions.

Vision is a very powerful being in the comics. Can you talk about what sort of abilities he has in the movie?

No! Yeah, a little bit. Well, we've already discussed he's incredibly good at punching which is key. He also has an ability to change his density and that's awesome and really exploited brilliantly by Joss, in terms of just really cool moments that Vision is able to do something that is really otherworldly. And it's kind of great, and he's discovering it all as he goes along.

He levitates a bit. Did you have to do wirework for those scenes?

Yeah. Have you ever been hung up in the air by your genitals? I have. It's great! There's a lot of wirework, and I enjoy it -- he said on the back of talking about his genitals. But no, they make it as comfortable as they can possibly make it, which is really uncomfortable. But it's as hard as doing something really uncomfortable for a lot of money: it's fine. And the results are so like, 'Wow, that's so cool!' It's all okay. It's another layer of the harness, to my mind, forget my genitals for a second -- I know that you were thinking about them -- for me, the problem is it's another layer of clothing that I have to wear.

Just as an actor, watching the superhero genre evolve, are you surprised at the amount of people that are getting involved in it? Did you feel almost compelled to find a place in these franchises?

I'm an actor, and I'm naturally blonde, so I don't tend to think things through very clearly. And I totally fell into it. I got a call, late on a Friday night from Joss saying, 'Hey. You want to be The Vision?' And I went, 'Yeah. Sure!' So I can't explain the amount of luck involved in that. No, I hadn't gone about cornering some market, thinking about it going, you know I need to get my niche in the superhero world. And frankly, for ages because I understood that once you were one character in a Marvel series, you were never another. I kind of let it go, you know what I mean? So that's cool. I'm Jarvis. And I do my thing, and I get a bag of cash. And I walk away like a burglar. And open my stripy outfit and my bag of swag, and that's great. And then this other opportunity -- we all had so much fun. I mean, they're a really nice bunch of guys, the Marvel guys. It's a good bunch of people, and we just had a lot of fun. So they chose to bend the rules, and I'm eternally grateful.

What do you love about working with Joss?

Well, there's a lot of dancing that goes on set, which might be the reason he's busted his leg. He's just -- never have I been more certain making a movie -- except maybe with Peter Weir, that somebody had a better idea than I did about what I should be doing. [Laughs] I mean, it makes you feel very safe to have that the ultimate fanboy also your director. He loves, loves it. He loves that world, and there's a huge amount of safety. And so when he says, "Oh, I think it should be a bit more like this." You go, "Hey. I get it. And even if I don't get it, I believe you, much more than I believe me. So let's do it that way." And he's incredibly relaxed. And having the time of his life making the film.

You've been around almost the longest in this world that they've created. From that small room with a bag of cash.

Say that again. It sounded so nice. Small room with a bag of cash. Heady days.

Did you ever think it would be the epic thing that it's become?

No. I had no -- I could lie and tell you, "Yes, brilliant. I thought this was the way to focus my career." But I didn't. I really didn't. I did it because it seemed like a fun idea at the time, and I make astonishingly simple decisions. And when I say simple, I don't mean like in a Zen way. I mean, like simple-minded decisions. I go, "Oh, that could be fun." And I go and do that.

Can you talk a little bit about what James Spader brings to the character of Ultron?

We have a scene, and it was the first scene that we shot together toward the end of the movie, and it was just -- even though you're talking in these very farfetched ideas, he managed to find something that was very human about the relationship that was happening between his character and my character. And it was really amazing -- you look into his eyes: he's there working. You look into his eyes, and it doesn't matter what he's talking about, you believe him. And he believed me, and it was really a great little scene to work on. And he was just so present which is difficult when you're in a fractal suit. And he's just got very arresting eyes, and you believe everything he says.

"Avengers: Age of Ultron" hits theaters May 1, 2015