Avengers: Endgame was a huge shake-up to the Marvel Cinematic Universe. The record-breaking superhero flick answered lingering questions, set up new story arcs, and marked the end of several beloved Avengers. And although the film's screenwriters say some of the characters' fates were established years before Endgame, they admit there were some last-minute debates surrounding some of the heroes' storylines, which could've drastically changed the MCU landscape.

Christopher Markus and Stephen McFeely dished on the alternative plot lines and reshoots during a recent Q&A with Vanity Fair. Among the highlights of the sit-down involved the death of MCU's first woman hero, Black Widow (Scarlett Johansson), who sacrificed herself in order to secure the Soul Stone. Markus and McFeely say the death sparked controversy among the crew, as they also considered having Hawkeye take the leap rather than Black Widow.

"We certainly thought long and hard about it. We knew we were killing the first female hero of the Marvel Universe," McFeely said. "We stupidly came up with these rules in the first movie—someone’s going over that cliff. So we had to decide. By the way, you had to easily love the person next to you, so we couldn’t send Steve Rogers and Hulk. So it's a puzzle of our own making, but it felt like it was the resolution of her arc, that if she could sacrifice herself for her new family and for half the universe, that was worth it to her."

He continued: "A number of women on the crew, when we said, 'Hey, we’re thinking maybe Hawkeye goes over,' said, 'Don’t you do that! Don’t rob her of this!' And then it choked me up because I think we would have a much different conversation if Hawkeye had pushed her aside ... She jumps on the grenade. I’m really proud of that moment. I don’t have any regrets. The only regret is that it comes at the end of Act Two. So you can’t really roll around in the grief because we’ve got another hour of movie and we haven’t solved the A-plot problem. So that’s the downside."

McFeely and Markus also revealed they had scrapped a scene that would've presented "Smart Hulk" much sooner; however, the screenwriters said the Infinity War idea would've taken away from the Thanos plot.

"There was a sequence in the first movie where they went into the places in the Doctor Strange universe called the mindscape and everyone faces themselves. It was great but had absolutely nothing to do with anything," McFeely said, adding the sequence would've centered on Hulk vs. Bruce Banner. "Banner meets the Hulk, I think in the arena from Ragnarok. Only one of them was getting out of there, and then that one showed up in Wakanda [in Infinity War] and he had merged. That merging that currently happens in [Endgame] in a diner, and he’s eating a huge stack of pancakes? That initially happened at the end of Infinity War."

The screenwriters said they had to do several reshoots for the first act of Endgame, as it had originally featured "Smart Hulk." They decided it made more sense for the character to undergo such a drastic change after the events of Infinity War.

"We wanted everybody to have this enormous journey in the five-year jump [after the Thanos snap], and to really see, in sometimes shocking ways, how the loss had affected them," Markus explained. "We hadn’t given Banner [a change] because we had transformed him earlier, and he had nowhere to go. And suddenly by needing to take it out of the first movie, it was the perfect thing."

You can read McFeely and Markus' full Q&A at Vanity Fair's website. They also touch on the alternate timeline questions surrounding Captain America's (Chris Evans) life with Peggy Carter, why they decided to keep Thor alive, and how they used custom-made superhero trading cards to map out storylines. 

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