That Superman/Batman movie remains something of a mystery, and everyone wants to make guesses as to what it’s really about (or which characters are in it, which might be the same thing). What we do know is that it will follow the events of Man Of Steel, where an alien leveled a major city and another alien snapped his neck, then proceeded to continue living on Earth in secret. You can see how things would be a little tense around the superhero watercooler now that Batman and Wonder Woman are joining the fray.
Director Zack Snyder has long been talking up the film’s ties to the seminal The Dark Knight Returns graphic novel, but given that the specifics are different (not everyone believes the book is canon, for example), it remains unclear as to how the material will mix with the established universe. Speaking with Popcorn Magazine (and translated by Comic Book Therapy), Snyder elaborates by saying, "The comic book will influence the history of [onscreen] Batman vs. Superman, on which the writer David S. Goyer and myself will work."
The average comic book fan remains curious about this, naturally. The Dark Knight Returns takes place in a dystopian future Gotham where an aged Batman returns to the streets. Though writer Frank Miller eventually wrote a sequel, many consider it the last Batman story ever told, and in the climax the Caped Crusader enhances his abilities and goes toe-to-toe with Superman, who is depicted as a company man serving the government’s interest. Miller’s Superman is a punching bag, a mixture of twisted 1980’s ideologies, and something of a joke in the source material. Unless they’re cherrypicking smaller elements of that story, it doesn’t make much sense why Warner Bros. would want to follow up Man of Steel where Superman is a dimwit go-along and Batman is an elderly, unquestioned (and possibly fascist) hero. Particularly if they’re looking to restart a bunch of newer franchises.
Part of that new franchise-building is sure to involve a Mr. Ben Affleck, who Snyder sees as his ideal Batman. He tells the magazine:
"Ben brings an interesting counterweight to the performance of Henry in the role of Superman. He has the experience necessary to paint the picture of an older and more advised man than Clark Kent, who bears the scars of a seasoned vigilante while retaining the charm that Bruce Wayne deploys when present in the world."
The main takeaway from this quote is that Affleck will be playing Bruce Wayne a significant amount, and that while Batman might be older and "seasoned," his Bruce Wayne will still be an attractive, possibly romantic figure. This seems obvious, considering that Affleck is expected to suit up as Batman for multiple films, the ties to The Dark Knight Returns suggests the new film will have a finality to it.
Of course, we’re still quite awhile away from this film being released (though we have no idea when they’re shooting). Maybe the story’s been changed enough that the film opens considerably after Man Of Steel, and Superman and Batman have already met and developed an opposition to each other? Bringing in The Dark Knight Returns pretty much guarantees the two of them will be at odds and that it won’t be pretty, but maybe, instead of building that resentment over the film’s runtime, the picture will begin with our assumed knowledge that the two are at each other’s throats. Whatever it is, we’ll find out on May 6th, 2016.