Keeping the continuity of the Marvel Cinematic Universe together over a decade and across 20+ movies is enough of a challenge. But when you start throwing in prequel movies, that’s when it gets even more challenging. That’s exactly the problem Avengers: Endgame writers Christopher Markus and Stephen McFeely had when penning the script: How to write Captain Marvel.

Carol Danvers’ origin movie, set more than two decades before the events of Endgame, premiered two months before Endgame. But the character was first shot on the Endgame set before she ever stepped foot on the set of her own prequel story. So how do you approach writing a character who is shot for your movie first but appears to audiences for the first time in an entirely different movie?

“God, I can’t imagine too many people in Hollywood have had to deal with that particular issue,” said McFeely in a recent interview with Backstory Magazine. Passing off the character’s torch smoothly required a ton of collaboration between McFeely and Markus, Endgame directors Joe and Anthony Russo, and Captain Marvel writer-directing team Anna Boden and Ryan Fleck:

“I remember sitting next to Anna and Ryan as they called action on Brie’s first day as Captain Marvel, which is on Endgame, and for the few weeks before that, they’d been around watching Joe and Anthony work because this is a big step up for [Boden and Fleck] in terms of size of movie.”

Carol Danvers/Captain Marvel takes on Thanos in ‘Avengers: Endgame’ (Credit: Marvel Studios)

Bringing Carol Danvers to life was tricky. She’s a complicated, complex character: Alternately cocky and vulnerable, compassionate and pragmatic. Her cocky swagger presented a new dynamic for the Avengers team, one that wasn’t easy to navigate for the fragile Avengers. Yet she is still incredibly competent and confident even 23 years earlier in her own story. Arguably the pound-for-pound most powerful member of Team Good Guys, her formidable superhero power set was also something that needed to be handled consistently. Captain Marvel needed to be able to singlehandedly take out Thanos’ ship in Endgame, but still needed her powers to be impressive and huge in her own origin movie. So the two teams talked and talked…and talked.

“We sat with them and showed them the draft and said, ‘Here’s how she works in our movie, and here’s how she sounds. Do you think this version of her, which is a version we had to decide on for our movie, which is 20 years after the hypothetical movie you’re going to make — have we done anything that would force you to do anything you didn’t want to do previously?’”

Did you get confused just reading that? Try being the four writers charged with introducing her to the MCU and working around that time jump, said Markus:

“I mean, that 20 years is both a weird thing to prompt us and a bit of a cushion in that there’s no telling what happens between the end of Captain Marvel and her appearance in our world. So, any fluctuations in character or appearance can be chalked up to the 20 years. I don’t look like I looked 20 years ago. We had to come to some consensus.”

Which was fine, pointed out McFeely, “but, like, if her behavior was 180 degrees [different], we were screwed.”

Carol Danvers/Captain Marvel goes Binary to take out Kree warships in ‘Captain Marvel’ (Credit: Marvel Studios)

Considering Endgame is now the biggest movie in box office history and Captain Marvel easily crossed the billion-dollar threshold, I’d say they managed it just fine.

Endgame is still in theaters if you want to catch it one last time before it leaves theaters for good.