^Or just have a few second re-cap at the start of the film.
"A young Bruce Wayne witnessed a common criminal murder his parents. Vowing to protect Gotham City from injustice he became The Batman".
Or a Seinfeld-esque:
"Bruce Wayne went to the opera with his parents, yada-yada-yada he dresses up like a bat and fights the criminally insane."
"A young Bruce Wayne witnessed a common criminal murder his parents. Vowing to protect Gotham City from injustice he became The Batman".
Or a Seinfeld-esque:
"Bruce Wayne went to the opera with his parents, yada-yada-yada he dresses up like a bat and fights the criminally insane."