“How the MCU Was Made” is a series of deep-dive articles that delve into the ins and outs of the development history, production, and release of all the Marvel Studios movies

In the grand scheme of the Marvel Cinematic Universe, the Avengers movies have always been its cornerstones. 2012’s The Avengers was the first movie to combine all the MCU heroes in one film, solidifying the idea of an interconnected universe. 2015’s Avengers: Age of Ultron marked a turning point of sorts, as our heroes started questioning one another and each individual’s faults rose to the surface in intriguing ways. So we knew Avengers 3 was inevitable and would be “important,” but no one could quite guess just how big the eventual movie would be. As the folks at Marvel Studios started mapping out what the future of the MCU looked like, they decided to use Avengers 3 as a way to finally pay off that Thanos cameo from the end of The Avengers…and then some.

A villain as big as Thanos couldn’t contain just one movie, and he wouldn’t just serve as any old antagonist. Thus, an idea was born: a two-part Avengers epic that not only brings Thanos firmly into the fold, but marks a conclusion for the MCU story that’s been told thus far. This is how Avengers: Infinity War, one of the biggest movies in history, was created.

To talk about the making of Avengers: Infinity War is to also talk about the making of Avengers: Endgame, but I’ll do my best to denote the differences (and there are many) throughout this piece. The inception point, however, is the same for both films. The idea was born on a Marvel Studios creative retreat, as recounted by Marvel Studios president Kevin Feige:

“We had a [creative] retreat. I initiated [them] in the summer of 2008—after Iron Man had come out and succeeded and we had announced Iron Man 2 and Thor, Captain America, and Avengers—where we just get away from everything, away from the phones, and away from the daily schedule to just focus creatively on the stories. We were on our third retreat perhaps, [around 2014] when we started talking about what would become Infinity War and Endgame, and in particular how do we pay off this purple guy that Joss [Whedon] set up at the end of Avengers 1 and start to intertwine him with these awesome Infinity Stones that we have that provide wonderful MacGuffins in these individual films, and when you put them together, we thought could be more. It was on that retreat, that was the first time we thought of doing two movies at the same time. Which has its pros and cons.”

In October 2014, fairly shortly after that retreat, Marvel Studios announced that Avengers: Infinity War – Part I would be released on May 4, 2018 followed by Avengers: Infinity War – Part II on May 3, 2019. At this time, Whedon was busy finishing up Avengers: Age of Ultron, which we would later learn was a pretty contentious production as he and Marvel butted heads on a number of issues. As the architect of the first two Avengers movies, he was the presumed frontrunner to spearhead the next two, but Whedon was spent after Age of Ultron and declined to return:

“Every movie I have ever made has been an ensemble piece of increasingly enormous proportions,” he says, sitting next to Feige in the editing suite. “That many balls in the air, it’s only going to get bigger with Infinity War. I’m not going to be able to give it what I would need to.” He rasps in a geezer voice: “It’s a young man’s game.”

Whedon later admitted that even though it was his idea to put Thanos in The Avengers, he was never quite sure where to take the character:

“Honestly, I kind of hung [Thanos] out to dry. I love Thanos. I love his apocalyptic vision, his love affair with death. I love his power. But, I don’t really understand it. He’s had a lot of power, and he was cool in the comics. And I’m like, Thanos is the ultimate Marvel villain! And then I was like, I don’t actually know what I would do with Thanos. So, I liked what [the Russo brothers] did so much, and I thought Josh Brolin killed it. And they did an amazing job of keeping that performance on-screen. But it wasn’t like I was like, here’s a set of directions. I was like, I’m gonna get through Ultron, nap for four years, and then I’ll come to the premiere. Which I did! It was like, this is so cool!”

So Whedon was out, but Marvel still needed someone capable of shepherding this massive undertaking. In April 2015, as filming was about to get underway on Captain America: Civil War, Marvel signed directors Joe and Anthony Russo to take the helm of Infinity War 1 and 2. That they were hired before even making Civil War speaks to the strength of not only their work on Captain America: The Winter Soldier, but also their working relationship with Marvel Studios throughout the development of that film and Civil War. Clearly the Russos and Marvel saw eye to eye on how to make these kinds of movies. The next month, the Russo Brothers’ Marvel screenwriters and MCU veterans Christopher Markus and Stephen McFeely were tasked with writing the two-part epic.

However, at this time Marvel realized that Infinity War would no longer be a “Part 1” and “Part 2” scenario, despite their previous announcement. Feige explained that shortly after revealing the release dates and titles in October 2014, Marvel realized they wanted to make two distinct movies, not two half-movies:

“We announced [in 2014] Infinity War Part 1 and Part 2. Very soon after that, as we started talking about it, we realized that’s not really what we were doing, and that’s not really what we wanted to do. We didn’t wanna do half a movie and then half a movie. We wanted to do two distinct movies, and we can talk about is it a cliffhanger or not at the end of Infinity War—and it’s semantics perhaps—but we always looked at it as not a cliffhanger. Thanos won and the movie is over. And now that you’ve seen Endgame it’s a tonally very different movie than Infinity War and stylistically very different than Infinity War, which again was always the intention, so very soon after calling them Part 1 and Part 2, we said, ‘Oh we’re not gonna do that.’”

As filming on Civil War got underway, Markus and McFeely got to work developing the screenplays and overall arc for both Avengers sequels, crafting a “blue sky ideas” document that was shared with the people at Marvel.

During this development phase, Markus, McFeely, and the Russo brothers briefly explored the comics storyline in which Thanos is obsessed with Death—who is a physical being—but ultimately found the addition of Lady Death as a character was too time-consuming in a story already packed with characters:

“It’s our responsibility to carry forward the story as it’s been set out,” said Anthony Russo. “You’re spending two-and-a-half hours with this many characters, so then adding in some character that the audience has no relationship to, having to explain the backstory of that character, making you care about that character, making Thanos care about that character, making that character interesting to the other characters … ” He trailed off, shaking his head.

Instead, they chose to adapt the thematic pull of that storyline into a different kind of motivation for the Mad Titan:

“We talked about his motivation, and much of the motivation connected to Lady Death is about balance,” said Feige. “It’s the balance between life and death, the belief that life was getting unchecked and out of hand and there needed to be a correction. We wanted to make that the driving force of Thanos and his backstory. That’s where Chris and Steve and Joe and Anthony found a more natural, grounded way … well, as grounded as a giant Mad Titan can be.”

Regardless, the idea behind Infinity War was to introduce Thanos as the film’s protagonist. It would be viewed from his perspective, as a way to compellingly introduce this Big Bad who’s been teased over all the previous films, but who audiences still haven’t formally met. McFeely explained:

“So Thanos will get the benefit of both [screen time and familial relationships]. He’s got daughters that he clearly has to deal with, and James [Gunn] did a nice job of setting the table for us, but we’re certainly going to run with that. And screen time. Very often, in the screenwriting weeds, we’re trying to get a character up and off the ground and so the bad guy tends to be a foil for the development of the hero, and that’s not the case here. If anything, it’s the opposite. Our heroes are foils for the villain, whose story we need to tell at large.”

In order to get further into the mindset of Thanos as the protagonist of Infinity War, Markus and McFeely attempted different tracks on multiple drafts of the screenplay. One featured Thanos as a narrator and delved into the backstories of his Black Order, clocking in at 250 pages. While this ultimately didn’t end up being “the one,” the experience helped them further flesh out the motivation of the film’s protagonist.

Structure-wise, the filmmakers hit upon the idea of approaching Infinity War like a smash-and-grab heist movie, with Thanos hunting down Infinity Stones and the Avengers playing catch-up the entire time. The Russo Brothers even cited Out of Sight as an influence on the film’s style and structure.