In the original Civil War storyline, Spider-Man is caught in the ideological struggle between Iron Man and Captain America over whether or not superheroes should register their identities with the authorities to continue to operate, with heroes who register being forced to work for the government in response. Iron Man is for it, Captain America is against it, and Spider-Man … well, he's conflicted.

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He's so conflicted, in fact, he starts on Iron Man's side — even revealing his identity publicly at a press conference to encourage other heroes to come forward and do the same — but eventually shifts loyalties and fights with Captain America. Throughout the entire story, he acts as the conscience for both sides and, indeed, the Marvel Universe as a whole. As Spider-Man goes, so do the readers' loyalties, because of the trust he's built with them over decades of shared adventures.

This is where the idea of bringing Spider-Man into a cinematic Civil War starts to stumble. While the audience is familiar with the character, he's never appeared in the Marvel movies before this; there's no reason for the other characters to care about him one way or another, never mind implicitly trust his moral compass. Far from being an underdog whom other heroes look up to because they're familiar with his never-give-up attitude, a Spider-Man making his first appearance in Captain America: Civil War would simply be a new guy in a costume. Given the number of superheroes Marvel has access to without partnering with another studio, it makes little sense to go for Spider-Man over, for example, Ms. Marvel or Nova.

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Indeed, the truth about Spider-Man's role in the Civil War storyline is that it can be filled by any number of other characters. In fact, given the setup of the Marvel Cinematic Universe, there are two obvious candidates for the position: Bruce Banner and Thor. (Hawkeye and Black Widow are, ultimately, untrustworthy when it comes to siding with the government, considering their past employment — let's be honest.) Both Thor and The Hulk have both the familiarity with the audience and the characters to step into the role Spider-Man played in the comic book, as well as the lack of guile necessary to make them suitably unbiased point-of-view characters for the audience. No Peter Parker — or Sony deal — necessary.

Ultimately, bringing Spider-Man into a Civil War movie serves corporate interests more than narrative ones, bringing Spider-Man "back" to Marvel being more of an accomplishment than anything that could be achieved inside the story. While there's an argument to be made for Marvel controlling the Spider-Man movie franchise given its apparent troubles at Sony, introducing the character into Captain America: Civil War wouldn't have served Spider-Man or the greater Marvel Cinematic Universe as well as either deserves.