'Avengers: Infinity War' Nearly Included Adam Warlock and a 'Giant F**king Snake' (Exclusive)

Chris Evans, Avengers: Infinity War
Marvel Studios / Insert by Jesse Grant/Getty Images for Disney

ET sat down with screenwriters Christopher Markus and Stephen McFeely to discuss writing a fake script and why Captain America is so hard to get right.

With only days to go until Avengers: Infinity War arrives in theaters, no one has been able to confirm too much of what is in the movie. (We know that a band of superheroes will take on an Infinity Stone-obsessed baddie played by Josh Brolin, and that's about it.) We now know at least two things that aren't in the movie -- one of which is "a giant f**king snake." "Just huuuge!" screenwriter Christopher Markus exclaimed.

Markus and Stephen McFeely are the writing duo behind all three Captain America movies, as well as Thor: The Dark World, which makes them uniquely qualified to pen the Marvel Cinematic Universe's 10-years-in-the-making crossover event. The writers sat down with ET over the weekend to talk about what was cut from their first drafts, what writing a fake script entails and why it's so hard to get Cap right.

ET: How much of the story and the specifics of Infinity War were you given by Marvel when you signed on to write these movies?

McFeely: Not much.

Markus: Less than you'd think. We had Thanos and his love of Infinity Stones and, basically, a blank check to bring in anybody who was available in the MCU.

McFeely: And to draw on any of the comics that were helpful and stray from them as necessary. We've always done that. Between Winter Solider and Civil War, we use what's helpful from the comics and then make a different thing out of it. So, we did the same thing here.

You introduce new villains in Thanos' Black Order. But were they any other characters from the comics you considered introducing in this, but ultimately didn't, for whatever reason?

McFeely: That we didn't end up? Yes.

Markus: Well, there are some in the original Infinity Gauntlet series that are-- Like, we didn't introduce Adam Warlock, because it's a massive backbend and you practically have to make an Adam Warlock movie to introduce him. He just can't walk onscreen. So, there was a brief moment where we were like, Ehhh..., and then we were like-- [He points to the movie's poster.] We have that many characters already! And then there were others we couldn't use. Like, Silver Surfer would have been useful, but we can't touch him. Currently.

McFeely: I don't want to spoil anything, because then if I tell you that they're not in it, you'll go "Oh, they're not in it." But there are certainly a handful of pretty crazy things that we put in for several drafts and took out.

Is there anything from your initial brainstorming or from those first drafts that got cut along the way that you wish would have made it in?

Markus: I will tell you something that you will go, "Oh, I'm really glad that's not in there."

Tell me.

Markus: A giant f**king snake. Just huuuge!

McFeely: Oh, we had a big snake. [Laughs] That's right.

Is that true?

McFeely: Yeah, we had a big snake in there.

Markus: We were sort of running on empty and we were like, "Snake? Big snake? Let's try big snake." And then everyone went insane.

In what context would a giant snake fit into this?

Markus: I can't tell you the context! Epic snake!

McFeely: We took a lot of swings at this movie and ended up with the right one. But it took a while.

You write the characters you think will be interesting to see paired together, but were there any pairings that came together on set that surprised you with how well they worked?

McFeely: Thor meets the Guardians is hilarious from start to finish. Hilarious. And that's a lot of improv and a lot of structure and a lot of script, but it's just this magical, little fairy dust thing of characters you love rubbing up against each other.

Markus: It's not a surprise, but we got to do more with them this time. Lizzy Olsen and [Paul] Bettany are great together. They just work perfectly together, and it was a pleasure to see them doing non-super scenes together. It was almost like filming a regular movie. A lot of the time, you know, people are on a crane, in front of a green [screen], and you're like, "I think we're telling a story," but there were a couple scenes where it's two people talking in a room and it was like, "These people are great!"

McFeely: It was lovely.

You've had the chance to write for many of these characters in Winter Soldier and even more so in Civil War, but you are writing for everyone in the MCU here. Was there someone that you initially found hard to nail down, hard to capture?

McFeely: Yes, to a degree. Remember what we're trying to do here is tell a story where 23 -- on the poster here -- have just enough of an arc, so that it's satisfying to watch and they're not just in the deep background waving. Some of those characters are beloved and are going to have a small arc and we resist that, like, Oh no, this is one of my favorite characters. This person needs to be in half the movie. But this is a movie where that can't really happen. So, what we said to ourselves is, We've got two movies to work with, so if your favorite character has a smaller part in the first movie, odds are they're going to have a much bigger role in the second movie. And that had to be OK by us.

In terms of the craft, of physically writing these characters, was there anyone who gave you trouble at first?

Markus: In a way, oddly for having written three movies, Cap was a little bit of trouble.

McFeely: He doesn't always come easy.

Markus: When you can dedicate the whole movie to him, his sort of single-mindedness becomes the whole point of the movie. He is the dead center of everything and he's going forward and people are trying to turn him, and he doesn't turn. When he's not the dead center of the movie, when he's in an ensemble, it's harder to throw just a little to him. Because you think, "Oh, he's not reacting. Why isn't he reacting?" Because he's f**king Captain America. He doesn't react. He punches you. So, he was a little hard to calibrate in a way that I didn't expect. I thought he'd be the easiest one, because we were like, "Ah, we know him." [Laughs]

"Because he's f**king Captain America. He doesn't react. He punches you."

Did you write Infinity War and Avengers 4 simultaneously, or did you write Infinity War, turn it in and then start Avengers 4?

Markus: No, we broke them together. [We] had two different boards and went, "That might be a better idea for that." And eventually had two movies and then wrote them one after another.

McFeely: In fact, we wrote the rough draft of one, wrote the rough draft of two, finished one, finished two and then I think turned them in on a Friday and the following Friday. We basically turned them both in to Marvel at the same time.

The title that you had on the cover page of Avengers 4, is that still the same secret title we don't know yet?

McFeely: No, it's always the secret working title.

Markus: I think the internet knows the working title of these movies, and it was just that 2. [The working title for Infinity War is reported to be "Mary Lou," so the title of Avengers 4 was "Mary Lou 2."]

How did it work writing these two scripts at the same time, seeing there will be two movies that come between them with Ant-Man and the Wasp and Captain Marvel? Did Marvel give everyone marching orders to keep everything straight?

Markus: No, we had to talk [to the other writers] and not dictate, but make certain requests like, "It would be fantastic if you could sort of have a scene that looks a lot like this at the end of your movie." But also that provided story in some ways...In a purportedly interconnected universe, you don't want to either bog everything down with the shared stories, so that nobody can have any fun, but you also don't want them to become so disconnected that it seems like they're no longer in a shared universe. But I think it really paid off for reasons that I won't explain and you'll understand a year from now.

What goes into writing a fake script? Or fake scenes for the script? I imagine they have to be realistic enough to convince whoever is reading that they are actual scenes...

McFeely: [Laughs] I know. That's why it's crap. Our assistant, Joey, for a couple of tries, would just do sort of a bad scene that could be the result of a fake thing over here. It got really complicated, you're absolutely right. Let's say someone died in the fourth scene, right? That's got a ripple effect throughout the whole thing! That means you gotta change the whole thing. You can't do that.

Markus: It's basically the scene with the only interesting thing that happened in it taken out. So, it's like if the door opens and it was your long-dead grandmother, the door would open and it'd be, like, the waiter and he brought you your coffee and left and then the scene ended.

McFeely: So you read that and go, "This is a terrible script!" [Laughs]

Have you had any actors disappointed when they found out one of the fake scenes was fake?

McFeely: I assume! I absolutely assume!

Markus: I think there was literally one point where at least one section of the crew prepped the fake scene. I remember there being some confusion like, "I brought all those things," and people were like, Oh f**k. Prep the blue pages. [After] a year and a half in Atlanta making this movie, I have no specific memories of anything, but it was like a scene said, "They bring in five cans of Coke," and it was supposed to be -- in the real script -- "He brings in five Infinity Stones." And someone showed up and said, "I got those cans of Coke." It's like, "Kev gave you the wrong script. OK, hold on, hold on..."

Anthony Mackie said the final fight sequence in Infinity War is 25 pages. Is that true?

Markus: Probably. When you say fight scene, it's not one thing -- it's a sequence. It could be a sequence intercut with another sequence. It's not like it's just two guys in a room hitting each other for 25 pages.

When you are writing one of these movies for Marvel, who seemingly has endless resources and the ability to do anything you dream up, do you worry about things like page count? Or about the production side of what you write?

Markus: Only after a while. We have occasionally been told, like, "That actor is not available" or "That actor is too expensive." But we've also been told, "Do that anyway. We'll get him."

McFeely: "We'll figure it out," yeah.

Markus: Story wins out. I remember on the very first one [Captain America: The First Avenger], there's a big fight on a train -- an awesome-looking train -- and there was a point in pre-production where we were told, "A train is out of the budget. We just can't do it. Can it be a truck?" And we rewrote it as a truck and everyone was like, "That is so lame." [Laughs] And suddenly the money appeared for the train, because the movie would have suffered had it not!

McFeely: So, we constantly write terrible scenes in order to get the scenes we want!