Robert Downey Jr looks set to join Captain America 3, which will translate Marvel's famous comic book tale Civil War to the big screen and pit Iron Man against Captain America in a bloody battle of ideologies.
It is huge news which will shape the Marvel Cinematic Universe (MCU) for years to come. What though, is Civil War, and with whom will other Marvel superheroes align themselves? Let's take a look.
It should be said however that I'm not indicating that all these heroes will be or should be in the film, I'm just speculating as to which side of the argument they would fall regardless.
What is Civil War?
The basic premise of Civil War boils down to the Superhero Registration Act, which the US government passes to attempt to keep the ever-expanding world of superheroes under some kind of control.
Iron Man supports the act, claiming heroes need to be given some sort of training and be held accountable for their actions. Captain America disagrees, claiming heroes need anonymity to protect their "normal" lives.
How will this work on film?
Looking at the roster of Marvel's current big screen heroes, many of them are known to the government and wider world. Those in any doubt will have become known following Black Widow's leaking of SHIELD files at the end of Captain America: The Winter Soldier.
Iron Man revealed himself to be Tony Stark, there's a museum in Washington telling everybody Cap is Steve Rogers, and Hulk's identity as Banner, Black Widow's and Hawkeye's will have become known after Widow's leak. Thor is, well he's just Thor.
All this suggests that the big screen version of the Registration Act may come with some noticeable clauses. Say for example, that the US demands these heroes act as government agents, that would be reason enough for many to not want it even if their identities are known.
Cap's argument could also include how this could affect future superheroes not yet known to the world.
The Original Avengers
Black Widow (Scarlett Johansson) could fall on either side of the argument, as could Hawkeye (Jeremy Renner). The pair being on opposing sides also creates dramatic tension, and seems a likely route to take.
Banner (Mark Ruffalo) is the secretive sort so it's easy to assume he'd side with Captain America, however he has always felt guilty for the damage he causes as Hulk and could side with Iron Man to help prevent other heroes causing such destruction.
Thor (Chris Hemsworth) plays no big part in the original story (a clone does but let's not get into that) and probably wouldn't have much of an investment at this stage. If however, having decided to live on Earth with Jane Foster (Natalie Portman) he may craft an alias so he can live something resembling a normal life. If that were to come under threat he could side with Cap.
The Side Characters
Both Captain America and Iron Man have friends and sidekicks in The Falcon (Anthony Mackie) and War Machine (Don Cheadle) who it's safe to assume would side with their bros. The Winter Soldier (Sebastian Stan) is an interesting one, while not really a superhero he will likely play a part in Cap 3 and therefore the Civil War story.
A post-credits scene for Cap 2 revealed that the Winter Soldier had realised his true identity, but his allegiance to his friend Cap isn't assured. He could play the role in the comics taken by Spider-Man, the character caught between Iron Man and Captain America who the two heroes fight to win over.
Avengers: Age of Ultron will also see the arrival of three new heroes: Vision (Paul Bettany), Scarlet Witch (Elizabeth Olsen) and Quicksilver (Aaron Taylor-Johnson). I'd wager the chances of them appearing in Cap 3 is high, but what of their allegiances?
Vision being – so we can assume – linked to Iron Man's computer JARVIS (same actor voices both) means he'll likely side with his creator, but the twins are another matter. They don't wear masks so have little to hide, so who they side with will depend entirely on the events of next year's Avengers sequel.
Ant-Man (or Ant-Men)
When Cap 3 arrives in 2016, Ant-Man will have debuted. The film set for next summer stars Paul Rudd as Scott Lang and Michael Douglas as Hank Pym, the new and former holders of the Ant-Man mantle.
If they were to appear in Cap 3 they could be split like Widow and Hawkeye. Pym might not be an active superhero, but he could still side with Iron Man as the character does in the comics. Lang meanwhile is younger with a long life he'd be losing if the act was enforced. The two could clash.
Guardians of the Galaxy
The Guardians of the Galaxy really stand alone in a far corner of the MCU. They will undoubtedly cross paths with the Avengers one day and return to Earth but that day won't be Captain America 3.
Doctor Strange, Ms Marvel, Black Panther. Having written this article I'm fairly confident Marvel's cinematic civil war will be more about the future of superheroes in that world than it is about the current stars. A Doctor Strange is certainly happening and it is believed Ms Marvel and Black Panther will follow, so could we see one of them appear in Cap 3?
It's a possibility. Stephen Strange was namedropped in The Winter Soldier and his film's shoot will crossover time-wise with Cap 3's, so there's potential there. The other two are less likely, but could be set up in some way by the events of the film.
Spider-Man plays a cruicial part in the Civil War comics but Marvel don't have the rights to use him on the big screen. Those rights belong to Sony, but recent reports have suggested that Sony and Marvel may be working on a deal to bring Spidey into the Avengers fold.
It's a long-shot, so it's best to assume it won't happen, but if it did then Civil War would be as good a place as any to introduce the web-slinger into the MCU.
Captain America 3 is set for release on 29 April 2016.