Batman V Superman: Dawn of Justice has - from day one of its announcement - been described as an adaptation of Frank Miller's seminal Dark Knight Returns story arc. For all the mysteries about Dawn of Justice's story, it has become increasingly clear with each new revealed detail that the Dark Knight Returns influences are very direct. The Batman V Superman teaser had a version of the Dark Knight in an armored suit that looked like it was ripped right off the page of Miller's book.
Today we have some new rumors regarding the film - this time concerning the backstory of Ben Affleck's Batman. While this is all just rumor at this point, the discussion that follows should still be considered as a POTENTIAL SPOILER.
— Samuel Otten (@ottensam) August 4, 2014
According to Devin Faraci over at Badass Digest, when Dawn of Justice begins, Batman will have existed for about 30 years - putting Bruce Wayne in his fifties, in terms of age (Note the grey temples in the set photo above). Batman has apparently operated from the shadows, and has never been actually seen or photographed; however, the Batcave and certain iconic objects (a Robin suit on display) will hint at the Dark Knight's long history of fighting crime. (SIDE NOTE: The report also notes that Wonder Woman has also been operating in secret for some time.)
This description fits in line with early details that claimed we would indeed see an older, seasoned Batman in the film - while later rumors pointed to that same weary Batman having retired from active duty in favor of commanding an army of crime fighting drones. One wonders if that latter part is also true.
The obvious question in this scenario is: Where was The Dark Knight when Kryptonians threatened the earth in Man of Steel? Well, if Badass is on the money, it could very well be true that Batman did something during the invasion - only it was on a small enough scale (within Gotham City) or was clandestine enough that it was never acknowledged on a national or global level.
Indeed, it sounds like Superman's emergence in Man of Steel may have been one of the late-game origins of a Justice League superhero. It would make sense: Superman and the Battle for Metropolis could easily be spun into THE milestone event that revealed the existence of metahumans to the world. After that, Batman, Wonder Woman, Aquaman, Flash, Green Lantern - all these characters who could have been operating in secret - would have a focal point (Superman) around which to gather and "out" themselves to the world.
Of course... that's provided that any of this is accurate, and you never know for sure when it comes to the DC Movie Universe.
Batman V Superman: Dawn of Justice will be in theaters on May 6, 2016
Source: Badass DigestJustice League: Snyder Says Fan Art is "Scary Close" to His Trilogy's End