Avengers: Endgame writers, Christopher Markus and Stephen McFeely, have revealed a key ingredient to the success of their films in the MCU: the lack of secret identities. The acclaimed duo then went on to credit the MCU's studio head, Kevin Feige with the blueprint for success.

According to Deadline, during a panel on Endgame presented by Disney, the writers dug deeper into the pieces of the Marvel films.

One of the main elements dates back to 2008 with John Favreau's Iron Man. In Iron Man, heroes were no longer restrained by secret identities. McFeely dove deeper, saying, "Think about the storytelling that allowed them, if they had decided to keep the idea that we had to keep that secret, now you’re telling certain types of stories.”

The writers believe that piece makes up only one-third of the formula, the other pieces revolve around using a character's strengths as their flaws.

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"We often think that the character’s flaw is their strength,” McFeely said. “[Captain America‘s] Steve Rogers, for example — he’s the guy that can do this all day. He is absolutely fixed in his opinion. He’s Gary Cooper in many ways, but that gets him in trouble. He won’t bend. He will sacrifice himself.”

Markus and McFeely are responsible for penning a number of films in the Marvel Cinematic Universe, including 2011's Captain America: The First Avenger, 2013's Thor: The Dark World, 2014's Captain America: The Winter Soldier and 2018's Avengers: Infinity War. 

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Directed by Joe and Anthony Russo, Avengers: Endgame stars Robert Downey Jr. as Iron Man, Chris Evans as Captain America, Mark Ruffalo as Bruce Banner, Chris Hemsworth as Thor, Scarlett Johansson as Black Widow, Jeremy Renner as Hawkeye, Brie Larson as Captain Marvel, Paul Rudd as Ant-Man, Don Cheadle as War Machine, Karen Gillan as Nebula, Danai Gurira as Okoye and Bradley Cooper as Rocket, with Gwyneth Paltrow Pepper Potts, Jon Favreau as Happy Hogan, Benedict Wong as Wong, Tessa Thompson as Valkyrie and Josh Brolin as Thanos. The film is available on Digital HD, Blu-ray and 4K UHD.