Zack Snyder Gives His Account on What Happened to Robin Prior to 'Batman v Superman'
One particularly damning image that became heavily pored over in the lead-up to Batman v Superman is the one in which Bruce Wayne stares at the glass case that hides the remnants of Robin's uniform, with Joker's signature scrawl adding insult to injury in a fantastically creepy way.
Director Zack Snyder has been remarkably open to questions surrounding his new DC universe, and he answered the question of what happened to Robin, at least to some extent.
"In my mind, it was that Robin had died 10 years earlier, during some run-in with a young Joker," Snyder told IGN. "So there was a fun backstory there to play with. I felt like the whole idea was that there had been loss and there had been sacrifice. In a weird way, he had sacrificed everything to be Batman.
"He doesn't really have a life outside the cave. I thought that including Robin, a dead Robin, was helping us understand that he's been on quite a little journey." The events certainly recall A Death in the Family, the comic in which Robin Jason Todd is brutally murdered by the Joker.
Source: Comicbook