Batman needs to be reintroduced, of course, but in a movie that will inevitably have so much else going on, starting from scratch with the character will seem very counter-productive. Everyone knows who Batman is now - the most recent trilogy only ended last year and the origin story for that franchise came in the first instalment only eight years ago - so going through all that rigmarole again would be a waste of time and, frankly, very boring. Start the film off with Batman doing his thing in Gotham, showing the audience what he's capable of and what he's about, but do so with Batman already being an established vigilante. We really don't need to see him travelling around the world, learning about the criminal underworld and honing his skills - we know how he came to be who he is - so let's just jump right in to the meatiness of this film and the prospect of Batman versus Superman.