(Warning - the following contains possible SPOILERS for Daredevil and Captain America: Civil War, not to mention a bunch of ten-year-old Marvel comics. Proceed with whatever level of caution that suggests...)
With Captain America: Civil War now less than year away from theaters, it's not too surprising that a whole lot of plot theorizing is taking place all across the internet. After all, with the film being (loosely) based on the classic comic book crossover event Civil War, and the recently-released Avengers: Age of Ultron seemingly leading directly into Cap's impending sequel, there's a whole lot for us all to go on - and to speculate about.
One of the biggest lingering questions?
What's Going to Spark the Civil War?
After all, when we left Captain America and Iron Man at the end of Age of Ultron, the pair seemed pretty darned friendly - with their disagreements earlier in the film seemingly forgiven, if not forgotten.
How, then, is that going to transform, in the space of a few short months, into all out superhero war?
Well, in the comic book Civil War, the whole thing is caused - alongside a growing public concern about the irresponsibility of some heroes, something seemingly also present in the Marvel Cinematic Universe - by a devastating explosion in Stamford, Connecticut, in which hundreds of people are killed.
Its cause? A battle between a group of publicity-seeking superheroes known as the New Warriors...
...and an explosive supervillain named Nitro.
With neither the New Warriors nor Nitro having yet appeared in the MCU, however...
How Will That Be Translated to the Cinematic Civil War?
After all, barring an introduction to the New Warriors and Nitro in the upcoming season of Agent's of S.H.I.E.L.D, there's very little chance that we'll actually see them appear in Captain America: Civil War. With the Hulk seemingly set to be AWOL - and his devastation of an African city in Age of Ultron having apparently been dealt with by Tony Stark's PR (and cash) injection, it looks as though everyone's favorite rage-monster won't in fact be responsible - but if not him, then who?
Well, there's been a lot of speculation that The Scarlet Witch will take over the role of 'powerful, uncontrollable super-human' - thus explaining her absence from the Civil War sides announced thus far - but what if Marvel goes in another direction.
Could the Root Cause of Civil War Be...Daredevil?
After all, the second season of Netflix and Marvel's Daredevil is most likely set to debut just a few short months ahead of Captain America: Civil War's release, which - combined with its readily available presence on Netflix - would make it a perfect place to set up Civil War, without requiring fans to go back and watch fifty-odd episodes of Agents of S.H.I.E.L.D. in order to catch up. Add in the potentially huge spike in Netflix subscriptions that the show featuring a key set-up for Civil War would likely generate, and you have yourself an eminently prudent commercial decision.
How Could It Work, Though?
Commercial concerns, of course, aren't everything - and it's entirely possible that Marvel will aim to keep the events of Civil War (including its origins) contained within the movie's running time. That, though, doesn't mean that Daredevil couldn't still be involved - or that his eponymous show couldn't feature the events in question too. After all, there's no reason why Daredevil season 2 couldn't end with a major disaster on the scale of the comic books' Stamford explosion, which could then also feature in the early moments of Captain America: Civil War.
If, say, The Punisher, Elektra, Daredevil and Bullseye all got involved in a major firefight in Hell's Kitchen, there's every chance it could end very, very badly - and that the vigilante likes of Daredevil and The Punisher would be blamed. What's more, with their superheroism limited to a small area, and utilizing far more violent tactics than, say, the Avengers, the crime-fighters would likely garner a whole lot less public sympathy when things went wrong.
With the central conflict in Captain America: Civil War set to be about who superheroes answer to, rather than the comic book storyline's focus on secret identities, opening the movie with a handful of costumed vigilantes answering to no one and getting people killed in the process could be the perfect way to set things up.
Plus, it'd provide the perfect opportunity for Tony Stark to befriend a - suddenly widely hated for a crime he didn't commit - young Spider-Man.
Or, y'know, it could play out completely differently...