Q: How did the idea of putting Batman and Superman together in one movie first come up?

A: Snyder: It was born from a conversation about what to do with Superman (after “Man of Steel”), what to face Superman off against next. I was also really interested in expanding the comic book universe. I think Chris (Nolan) did an amazing job with those three Batman movies he did, but, to me, those worlds are very self-contained. If Green Lantern came into the Dark Knight movies, you'd be like, “That's weird.”

I really wanted the “Man of Steel” world to be a world where other DC characters could exist. So I was talking to Chris, and I said, almost off the cuff, “What if Batman was the bad guy?” And once you say that, you can't take it back. I mean, who's a better guy to fight than Batman?

Q: The obvious question you face right away is how do you have these two battle? Batman has amazing fighting skills and weapons, but Superman is basically indestructible and could just throw him out to Saturn if he wanted to.

A: Affleck: It's a credit to what a good guy Superman is. Put it this way: It takes an hour of storytelling to make it plausible. You don't just ring the bell at the beginning, and they go out and start fighting like “Alien vs. Predator.”

Snyder: It's cool to have the setup where it's like, “This guy is a man. This guy is a god.” They do fight, and the fight is compelling. That's the fun, that you have these two titans of that universe, and we got to use that playground to set them at each other. And the mythology is so rich, you can mine it all day.

Q: Ben, you've said you were initially reluctant about playing Batman. You once said starring in “Daredevil” “inoculated” you from ever playing another superhero.

A: Affleck: I just thought it wasn't a good fit. But I went in and met with Zack and saw this kind of visual 360 of posters and drawings and action figures and animatics, and I was totally blown away. All of the sudden I saw something I'd never seen before and hadn't even imagined. This genre is the biggest forum for telling stories in the world right now. You get the biggest megaphone. But this movie is using the genre to explore really interesting themes. And just for me personally — you mentioned “Daredevil” — I thought, “I want to be in one of these movies that works.”

Q: There have been several actors who've played Batman. How did you set about making him your own?

A: Affleck: What I liked about Zack's vision for it is that it's sort of an existential Batman. He's a guy who's not actually in the throes of being Batman but looking back and asking himself, ‘Was it worth it?' He's a graying Batman and more of a slugger and more of a man because he's more vulnerable. He's feeding some hole inside him — (burning a brand into) criminals at night, going to these underground fights, having some woman in his bed from some random encounter. He's functioning but not in a healthy way. He's a haunted and broken guy.

Q: Henry, this movie brings some darker dimensions to Superman, whom we often think of as the simple embodiment of pure goodness.

A: Cavill: Right, certainly in some previous live-action adaptations of Superman he's been — I don't know if “simplified” is the right word, but something around there. But there is a complexity to Superman that is very prevalent in the comic books. It's just a matter of bringing it out, which is tricky to do.

Q: “Deadpool” was made on a much smaller budget and wasn't necessarily expected to be a massive hit. This movie is almost the opposite of that: The budget and the expectations are huge. How do you see the stakes?

A: Affleck: Look, in the broad sense, from a long-term portfolio perspective, Warner Bros. has already won. They own this vast underexploited (intellectual property) that is DC. They're going to make all these movies regardless. Will every DC movie be great and be successful? No. Would it be good if “BvS” works for them? Yes, obviously. But if any one of the movies doesn't work, it doesn't mean it all goes away. “Green Lantern” didn't work, and Green Lantern is going to come back and work for them.

Zack spent two years of his life on this movie, and we put in months and months. We are truly, deeply invested in this movie. We want the movie to be good. We want to be proud of it. I want to make a movie that my kids think is cool.

josh.rottenberg@tribpub.com