When Batman v. Superman was first announced, a good portion of people brushed it off as a 5 minute fight before the two heroes team up to fight a bigger evil. While the unity may still occur, it does seem that Bruce Wayne/Batman, played by Ben Affleck does have a good reason for chasing after Henry Cavill’s Superman.
In 2013’s Man of Steel, Superman’s final battle with General Zod leaves Metropolis in ruins, with (as many viewers pointed out) many civilians most likely dead. In a flashback sequence, it appears Wayne was nearby as the fight took place. It is also heavily implied that one of the many buildings destroyed was Wayne Enterprises property, meaning Wayne lost workers and friends that day.
Another criticism that some people voiced was the idea that Batman would be introduced so suddenly, but appears in this universe, Batman is already an established part of the mythos but retired. Meaning Batman v. Superman would not really be an origin story, as a graffiti’d up Robin suit (presumably by the Joker) is seen in the trailer bearing the message, “HAHA Joke’s on you Batman”. Whether this means Jared Leto’s take on the clown prince will appear before Suicide Squad remains unknown.
For more, check out the trailer below.