With the announcement that Robert Downey Jr is joining Captain America 3 in some variation on the Civil War storyline some of you are probably asking, "What the fuck is Civil War?" I'm here to explain it to you.
First it's important to remember that one of the cornerstones of Marvel Comics is superheroes fighting each other. Marvel fans love this. It's a standard Marvel trope for two heroes to accidentally start brawling when they first meet, or on multiple future meetings. The idea of heroes battling heroes was so popular and such a part of the Marvel Universe that the 1982 Contest of Champions miniseries was basically just an excuse to get the heroes in a ring battling each other. Intriguingly there were two teams in that comic - one headed by Captain America, the other by Iron Man.
Jump ahead to 2006 and we have the Civil War series, a comic that has really set into motion the last seven years of the comics universe. The premise is incredibly simple (and actually ripped off from the X-Men's Mutant Registration Act storyline of the 80s): vigilante superheroes cause so much destruction the federal government demands they be identified and registered for both legal and insurance purposes, and that they act under the direction of the US government. It all starts when the fourth-string hero Speedball and the villain Nitro get into a battle that destroys many blocks of a small town, including a school. 600 people die, 60 of them children.
That leads to the passage of the Superhuman Registration Act. While Iron Man is initially against the Act, he decides that at some point in the future someone's going to fuck up even worse and whatever legislation is passed in that case will be even more draconian. The SRA makes anyone with super powers, ability to access magic or 'exotic technologies' register their true identity with the government and receive training to use their powers better. But Captain America resists, believing that autonomy and secrecy allow heroes to do what they must while protecting their personal lives and their loved ones. Of course his identity is already known to the government, but for Cap it's all about the principal.
When the act was passed the superhuman community was split down the middle, with many refusing to register. But they kept up their activities battling villains, even though their battles would often end with pro-registration heroes and SHIELD agents showing up to detain them. Iron Man convinced Spider-Man to reveal his secret identity as a PR move (a story point that had to be massively retconned later because it was a huge mistake) while the anti-registration heroes were forced to go underground.
Shit got real when Cap led his side in an ambush against Iron Man's team. Meeting under the pretense of a peace talk, Cap activated a device that depowered Iron Man's armor and the two factions went into a full-on superbrawl. During the battle the anti-registration hero Goliath was killed, and not long after it was revealed that Mister Fantastic had been working on a prison in the Negative Zone in which to house anti-registration heroes forever. It was getting way, way dark.
So dark, in fact, that Spider-Man switched sides and joined Cap and friends. Things kept escalating until the two sides joined battle again in the middle of New York and Cap and Iron Man went toe-to-toe again. Cap had Iron Man on the ropes and could have finished him... but opted instead to surrender. That leads to a de-escalation of hostilities, some amnesties being granted and Tony Stark becoming the head of SHIELD. And, while Captain America is led in chains into court he is assassinated, leading to the Winter Soldier taking over for Steve Rogers.
That sounds pretty good, but the execution in the comics kind of sucked. Still, the basics work... except they couldn't work in the Marvel Cinematic Universe. For one thing, no hero has a secret identity. There will be a Daredevil by the time Cap 3 comes out, but it makes no sense that this whole thing would be over some dumb guy doing parkour in Hell's Kitchen. And the main beats simply couldn't work for a number of reasons, chief among which is that we know Cap 3 will continue the story of Cap trying to find and help Bucky.
So what we're left with here is the most bare skeletal aspect of the story: Tony and Steve disagreeing about being superheroes. They can disagree over the superhero's role in the world, over the idea of whether or not superheroes should be independent. In The Avengers pretty much all of Earth's superhumans operated under the jurisdiction of SHIELD, but by the time Age of Ultron rolls around they're privatized, being supported entirely by Tony Stark. To whom are they accountable? To whom do they answer when things go tits up? We have a police force not only to protect us but to have those protectors be regulated and answerable in case of malfeasance. Why should superheroes be any different?
That makes for an interesting kernel of an idea for Cap 3. It's also dramatically excellent in the longform MCU - the very selfish Tony Stark finally sees his responsibility to the world, while the soldier Steve Rogers realizes that power cannot be centralized under authority. This position would actually align Cap with the framers of the Constitution, who were terribly suspicious of the idea of a standing army. Done well either side can be compelling and make perfect sense to the viewer - it would be exciting to have friends walking out of the movie debating about who is right, with each having strong arguments.
It's important to realize that there is essentially no chance that a Civil War story in the MCU resembles the comic book Civil War, any more than The Avengers: Age of Ultron resembles the comic story of the same name (which takes place in an alternate dark future). The title and the barest concept of heroes at odds would be all that likely carries through, although Cap's fate could be replicated onscreen, especially as I've heard time and again that the working title of the movie is Fallen Son.
In fact it's hard to imagine how the comic storyline fits in with what we know about Cap 3, straight from the Russo Brothers - that it will continue the story of Winter Soldier and feature Crossbones. We're looking at a film that will be enormously different from its source material, except for Cap and Iron Man going head to head.
Some outlets have been claiming this film will start a Civil War storyline across the MCU, but that doesn't feel right to me. I think, like The Winter Soldier, it will have fallout that will define the MCU's next phase, but it will not be some sort of multi-part story spread over many films.
Finally, some have already wondered if the MCU is ready for this story. It definitely is. If you look at each phase as a TV season you'll see that Marvel's ending their third season with Cap 3 and Avengers 3. The stories have, in a larger emotional sense, been leading up to this:
Phase One introduced the heroes and then teamed them up as The Avengers.
Phase Two sees the heroes tested as individuals but remaining pals, as we'll see clearly in The Avengers: Age of Ultron.
Phase Three will have the heroes dealing with the final conflicts of their own stories and then being tested as a group. Their friendships will shatter, the trust will be gone. The good feelings have been established enough to make this shattering of The Avengers carry a lot of weight.
That leads to Phase Four, where the heroes will be forced to finally come together to face a threat unlike any they've ever known.
It's dark, but in the right way, coming from characters and building towards an eventual redemption. It's like The Empire Strikes Back, the beat of hopelessness that makes the eventual victory all the sweeter. What makes the Marvel Cinematic Universe great is that it's fun, but that fun must be put through the wringer every now and again otherwise you have a series of films without stakes or meaning. Your heroes have to get their asses handed to them, and it's more dramatic if they're handing themselves their own asses by making mistakes. It is simply great drama done in a longform way.
As for Spider-Man... HitFix has reported the rumor that Marvel and Sony are in talks to bring Spidey to the MCU, and his major role in the comic version of Civil War has set off speculation in a big way. I don't think this is happening, but I have learned never to underestimate Marvel Studios. Still, I'd be shocked if they shoved Spider-Man into a movie that is already pretty stuffed.