A critical fan theory concerning Joker in the DC Extended Universe and the fate of Robin has found support from the craftsman of the story alluded to in Batman v Superman, Zack Snyder.
Snyder seemed to confirm speculation Jared Leto’s Joker killed Robin and burned down Wayne Manor when the director liked a post on Vero making the case.
According to the theory, Joker brutally beat Robin (Dick Grayson, says Snyder) and set the body on fire. He did this inside Wayne Manor, causing the house to burn and wind up “looking like that” in BVS.
Further, it’s contended Joker knows Batman’s true identity but refuses to reveal it to the world because all he cares about is keeping the games between himself and Batsy going.
So that’s the story behind the “HaHa Jokes on you Batman” spray-painted costume endorsed by Snyder in a small way. He still has yet to fully approve or publicly confirm it, though.
In 2018, also on Vero, Snyder offered a slightly different explanation for the Manor’s disrepair.
“I think his father commissioned the lake house as a gift to his mother, a place built by her favorite architect, and she loved it. When Bruce turned 18, he moved in. He ordered Wayne Manor to be left to decompose,” he said.
That could only be one side of the story, leaving room for Snyder to expand on it and work in the fiery death of Robin. Jared Leto is present for the Justice League reshoots so they may do just that.
The Snyder Cut’s Joker is alleged to be darker and that might mean he does something cruel and vicious. Reports augur there will be some kind of flashback involving Robin, but we have to wait and see.
Back story verifying or refuting the theory above could play out as well in a miniseries starring Ben Affleck as Batman. Jared Leto is rumored for that if it happens. Gaps may get filled and the saga of Batfleck would conceivably wrap up there.
Details left out of Suicide Squad’s Ayer Cut could fill in some of those gaps too but we shouldn’t hold our breath on seeing that on HBO Max anytime soon.