When Joss Whedon’s Avengers: Age of Ultron was filming in London last summer, I got to visit the set along with a few other reporters. Like most Marvel set visits, they let us talk to the entire cast and watch filming. While the production was guarded about what they were willing to tell us, we learned a ton of cool secrets behind what’s bound to be one of the biggest films of 2015. In The Avengers sequel, Iron Man (Robert Downey Jr.), Captain America (Chris Evans), Thor (Chris Hemsworth), Hulk (Mark Ruffalo), Black Widow (Scarlett Johansson), and Hawkeye (Jeremy Renner) reunite to stop Ultron (James Spader) from carrying out his sinister plan. The film also stars Elizabeth Olsen, Aaron Taylor-Johnson, Paul Bettany, Don Cheadle,Andy Serkis, and Samuel L. Jackson.

While on set, I participated in a great group interview with Joss Whedon. He talked about how making The Avengers sequel was different from the first film, the look of the Vision, when he first started coming up with ideas for the sequel, the success of the Hulk in the first film, Ultron, Quicksilver and Scarlet Witch, Hawkeye, James Spader, and so much more. Hit the jump for what he had to say.

Before going any further, if you have yet to see the Avengers: Age of Ultron trailer, I’d watch that first.

Question: What was your head like going into this movie and what were you set out to do differently?

JOSS WHEDON: Yeah, the first one, it was a raggedy me that made that film. It did take a lot out of me. Going in this time, I just had to sort of recalibrate my entire existence and throw myself into it more wholeheartedly and say, “Okay, I’m actually going to make it harder to make from the last one. I’m gonna just invest myself in every part of it, in every production meeting, in every location scout, and every question about a prop that I’d like to avoid. I might even work harder on the script. There’s nothing in it that I’m not going to let tear me apart. I’m just gonna give myself up to it… like a Christian to a lion.

I’m curious about the look of the Vision and how it’s going to evolve. Are you still working on how it’s gonna look?

WHEDON: No, we make them as close as we can. The stunt guy, we have to make allowances for the shape of his face and padding and things that we’re putting on him, but they’re not meant to look different. Basically, what usually happens is, one of the guys, Ryan Meinderding or one of the guys on his staff draws something unbelievably beautiful, and we try to create that in real life, and it takes a long time. The first tests were very Violet Beaurogarde. It really took a long time to get to a place where we felt like… even though we will work on him in post… he walks on and we go, “Oh, it’s The Vision! My God!”

That was our reaction when we walked out there.

WHEDON: Yeah, and of course, I wanted Paul to play this part since before I wanted to make an Avengers movie. Let’s face it, it’s about cheek bones, people.

When did you first start coming up with ideas for the sequel, and were your first ideas the ones you’re actually making?

WHEDON: Yeah, before I took the first job, I said, “Well, I don’t know if I’m right for this or if I want it or you want me, but in the second one, the villain has Ultron and he has to create the Vision, and then, that has to be Paul Bettany.” (laughter) It took me three years before I could tell Paul that I’d had that conversation, but after that, I stopped. I was like, “That would be cool if there’s you have Ultron and you have Vision and Paul played him, and Scarlet Witch and Pietro, definitely. They’re from my era, they’re very different, their powers are different, it’s not all punching, it gives a different palettes, we can do more interesting things, it’s fun; those things were absolutes.

But then I didn’t actually want to make the film necessarily. I was ragged from the first one, and so I just turned off my brain. I was like, “Do not think of cool ideas for the next one. Just get through this.” But after a few months when they talked about actually paying me, I would say, “Alright, this is now something that makes sense in my life; do I have anything to say?” And so my agent called. I was in London, and he called and said, “You know, there’s a deal that’s worth talking about. Time to start to thinking about whether there’s a movie,” and I’m going, “Alright.” I went to a pub, and sat down with my notebook, and about forty-five minutes later, my notebook was filled. And I texted my agent, “Yeah. I have so many things to say.” I was kind of surprised. It took me unawares. It was very beautiful.

Introducing characters like Pietro who I know is a favorite of yours. When you’re inserting them here, are you always thinking, “I’m inserting this character and now I’m building this huge arc that is going to play out over phase three or phase four”?

WHEDON: Yeah, I mean, you’re aware of that, but you sort of can’t be slavish to it. One, I think the biggest mistake in the world of franchising is… well, as he says in Gattaca: “Know how I beat you? I didn’t save anything for the way back.” Don’t worry about, “Well, we can do something next time.” It’s like, whatever you want, get it in there. Not that we can do everything with every character but you wanna get an arc that’s complete. You don’t want people to think “Wow, that’s part one of something” or even part two of something. I have been lambasted for criticizing Empire Strikes Back. I wasn’t criticizing the film which I love very much. I was saying that the experience of having a movie not end, it’s weird for me and kind of disturbing. For me, I need to get everything in that I need from him, and then if he continues, either I or somebody else will need more. These characters have existed in their iconic narratives for longer than I’ve been around, which is just really long.

When you filled your notebook up are the ideas you wrote down the ones you’re doing?

WHEDON: A lot of them, a lot of them. And there’s some that you’re like, “This is the heart of the… no, that doesn’t work.” But yeah, generally speaking, it’s character stuff, really. It’s not necessarily… it’s definitely not plot stuff because that’s the stuff that you can pull out of yourself with agony. The character stuff of, “Oh these people connect and these people can’t connect,” and we can tear them the part and bring them together, and you know, have this insight into the character, that’s the stuff that makes me wanna make a film, not like, “Oh and then there’s a cool plot twist.” I have to have a mind for that.

Can you talk about the success of the Hulk in the first film? Did you want to preserve him for the world of the Avengers?

WHEDON: Well, I wasn’t the one who said, “Don’t make a Hulk film” or anything like that. Kevin said to me, “We think right now it’s good to have somebody that you can only have in the Avengers.” There may be rights issues, I have no idea. Everybody loves Mark. He’s phenomenal, but the fact there hasn’t been a Hulk since that Hulk doesn’t suck. My job is hard enough, you know. Cap’s had a movie, Thor’s had a movie. Everyone’s gone through big changes, Iron Man’s had a movie, so I have to juggle everybody’s perception of that while still making a movie that you can see having not seen any except the first Avengers or not even that.

You said that the movie is much bigger this time around, so how much bigger?

WHEDON: I don’t remember saying it was bigger. I remember saying it was harder… but it is bigger. The cast is bigger. The scope is bigger. We have more to work with, not that we’re trying to spend more. In fact, we’re trying to avoid bloat wherever possible. But with this, we’re on a broader canvas, we’re in more countries. We have a bigger world to work with and a bigger world for them just to be in. Once they exist as a team, we have to deal with what everybody thinks about that, and what that means to the world. So it’s not as simple as it was.

Is there a kind of a Dr. Frankenstein and his monster thing happening with Tony Stark and Ultron?

WHEDON: In the Marvel universe, there’s a lot of Frankensteins. Steve Rogers himself, one of the better-looking Frankensteins of our era. Yeah, there’s always an element to that. There’s a lot of people, whether they’re trying to do good or bad, who think they have the next big idea. And the next big idea is usually a very bad one.

You talked in the past about how the Hulk is probably one of the harder characters to adapt into a live-action film. Giving him a bigger role in this film I’m curious exactly how are you handling that? We know that Bruce has his hands in the creation of Ultron, so I was curious if you can talk about the expansion of Hulk’s character and if we’ll hear him talk more this time around?

WHEDON: His monologue about his childhood is very poignant… and lacks pronouns. No. The talking thing is something that I sort of pitch it and I take it away. It’s moment to moment. Done wrong, it could kill ya, so I’m pretty leery about that. But Banner, you know, has a significant role, and the Hulk, we really held back on him for a long while in the first one. And said, “There’s something terrible coming that you’ll love.” Which is what makes the Hulk so hard to write is that you’re pretending he’s a werewolf when he’s a superhero. You want it vice versa. You want to see him, Banner doesn’t want to see him, but you don’t want Banner to be that guy who gets in the way of you seeing him. So the question is, how has he progressed? How can we bring changes on what the Hulk does? And that’s not just in the screenplay, that’s moment to moment, because even when they are putting in temp mix they have a library of two roars. “Aaarrgh! Uuurrgh!” What if he wasn’t roaring? I’m angry, and I’m not roaring. I’m being very polite to a lot of reporters and I’m filled with rage. (laughter)

Quicksilver and Scarlet Witch, you brought them in, and you have the Vision. That’s like a second team like Hawkeye and Captain America in the old days. And they’re not mutants now. Are you bringing them in with the age of miracles? Are they going to be an Inhuman thing? Is there an explanation besides just war technology?

WHEDON: Strucker’s been doing experiments, and he’s got the scepter, and he’s been using alien tech to do them. It’s kind of where I landed with that, but look for an exciting retcon in Avengers 6!

In terms of coming back to write a sequel, now you’ve worked with this cast and you’ve had that first experience, does that help you find the voice the second time around? Are things that you knew that you wanted to do specifically because of the actors?

WHEDON: Yeah, I mean, most of them had already played the parts before even the first one, and it’s hard not to hear Robert Downey in your head. He’s very distinctive. It’s been easier. It’s been easier for me to give them what they are comfortable with, and also to let them sort of mold stuff a little bit, you know? There are certain things where I’m like, if you want to make this more your own in some way I haven’t thought of yet, we have mutual trust, where if I say, “I know this feels weird, but I need it.” And they will back me. And if they say, “I feel like I could come at this differently,” I will back them, because, you know, we’re creating those characters together, and they will always see something that I missed. And they will always have some little insight, especially when all ten of them are in a room. I’ve got all of these enormously interesting actors playing enormously interesting characters. I’m not going to get every nuance of everybody, and somebody will say, “Wait a minute. Aren’t I dead already in this scene? Should I have so many lines?” “Right, good point. Sorry.” By the way, please don’t turn that into a headline. I’m so sick of reading about killing people. (laughter) A joke.

Where’s does Wanda fall in the sort of tradition of the strong but somewhat damaged-by-powers characters that you’ve written in the past, like Buffy?

WHEDON: Well, you know, “strong but damaged by power” describes every person in this movie. It may, in fact, describe what the movie is about. You know, the more power that we have, the less human we are. Her damage pre-dates her power, and these kids, they’ve had a rough history. But is she in an idiom with which I am comfortable? Why, yes sir, she is. (laughter)

We’ve gotten a glimpse of the relationship between Wanda and Pietro and we know that Iron Man and Ultron are tied together. Was there an organic way to bring those two stories together? They felt like two separate stories in a lot of ways.

WHEDON: They did. They did, and that was, you know, a concern for Marvel for a long time, but a lot of the working out of the story was how do we get these things connect? I’m not probably going to explain that, but it’s very important to me that they do feel like part of the same story, and part of the same universe, and all their origins are tied up in each other.

During Phase Two, Hawkeye wasn’t around too much, and I’m curious if we’re gonna find out what he’s been up to in this film?

WHEDON: Um, yeah, we are. ‘Cause something’s up with that boy. That’s all I’m gonna say.

About the character of Ultron, when you have a guy like Spader who has an incredible presence, which I imagine lends itself to the character quite well, but I’m curious, how is he acting in a general scene amongst humans, his open philosophy, how that kind of translates to the screen?

WHEDON: Well, Ultron feels a certain distance from humanity, and the day Spader got here we put on the mocap pajamas, a giant thing with red dots on it for his eye line, and a giant pack, and a helmet with two cameras in his face with lights to record his performance. He then did a scene with Scarlet, but not looking him in eye because she was looking up in his eye line, nor could he see her because he had two lights shining in his face, and he had his glasses on. Therefore, he has a certain distance from humanity, too. God bless him, he was wonderful, and very game and has been the whole time. Very interested in the mechanics of the mechanics, and of you know, finding the humanity. He and I share a genuine love of this version of Ultron, and he has an innate eccentricity in his delivery that is everything that I had hoped Ultron would be.

How is he different from other villains you’ve seen in superhero movies?

WHEDON: I think for me, there’s always a point where I’m writing them where I’m like “They’re right! The Avengers suck! We got to do something about that. We got to take care of these guys.” Hopefully, you will come out of this, if not agreeing with him then getting him, and getting his pain, which leads to a lot of damage, and some humo. How’s he different? I mean, villains are different from each other. The important thing for me is he’s not this external thing. He’s not Independence Day. Not that I’m criticizing that movie, but it’s not like we spent some time on the alien going “Oh, I hate that Will Smith! Punched me right in the face my first day there!” (laughter) When he’s in his scenes, you want to feel like he will never understand that he’s not the hero.

With Quicksilver, did the X-Men Quicksilver that just came out change your visual approach to anything? The speedshots?

WHEDON: Not really. I mean, there’s some things that we now would probably care to avoid just so that we’re not… But we were never doing the same version. Obviously, at some point we’ll go into slow-mo because that’s what’s fun about a super-speedy guy. For me, what’s fun about Quicksilver isn’t necessarily seeing Quicksilver, it’s seeing the Avengers the way he does. They really took to the mattresses with that one scene, but he’s just a very different guy in ours and I think we’re just kind of proceeding as planned.

Could you talk about working as a filmmaker on a studio film? You and James Gunn have worked within the studio system before, but you also were working with your own characters at that time. What’s it like playing with someone else’s character in a studio film like this?

WHEDON: Well, I’m aware of can’t do that or say that. I know that I work for Disney. I know that I want children to see this film and not have nightmares about it. But I understand the parameters, and at the same time, I don’t know of a place that would let me make a film this personal for this much money. Marvel, I feel like they treat the movies, or they have for me–my experience of it–like they treat the comic books. When a new writer and artist comes on board, they have their own vision of what it is, and they respect that, because they can’t say, “Rom Lim, draw like John Buscema.” He can’t. I get to make a movie that’s very much about the things I need to talk about, and sometimes, I forget that during the whole process because these characters are so dear to me from before, and they belong to them, but then when the thing shakes out, it’s very much the movie I dreamed of, and that’s why I’m back.

When making The Avengers, you already knew that Ultron’s gonna be the guy. The same with Vision and the twins as well. Are you already trying to plan out in your mind that every character leads to something else? Are you already thinking big ideas for how stuff will connect down the road into Avengers 3?

WHEDON: There comes a point in filming when you are writing, filming and editing, and, you cannot make a grocery list. I haven’t had a good idea about anything. I’m so excited that I’m wearing underwear, that I got that right today. Every now and then, it’ll happen, but right now we’re just past the halfway point, and I’m still finessing and finessing and finessing, and I got nothing. I do this, I go home, I rewrite, I go to sleep. I do this, I go home, I rewrite, I go to sleep.