This sets up a mystery that I think will remain unsolved for the sake of the series' lead not being overshadowed by the venerable caped crusader, but how could it be solved...in an interesting way? Why would Bruce Wayne abandon Gotham for three years? And where's the rest of the Bat-family in the context of this series? None of the Robins or Batgirls or even Commissioner Gordon...
Where is everybody?
Oh...there is an answer...but it's a dark one..
Y'know...people have been saying Batman and The Joker are 2 sides of the same coin for decades. I would say, in terms of superficial baseline ethics, yes, I agree. They like gadgets. They leave notes and calling cards behind. They dress in costume. The vehicles they drive are named after each other, respectively. They're both tricksters. Batman can be just as tricky as the Joker, but the idea of Batman becoming a Joker is how you get "The Batman Who Laughs", a Batman from an alternate/parallel Earth, set in "Dark Multiverse", who becomes the Joker after killing the clown prince of crime, only to wind-up unwittingly exposed to the toxin behind his arch foe's transformation. He immediately dispatches all the Bat-family members and his allies in the Justice League and the DCU before turning his attention to the multiverse itself...that's as far as I want to go with the recap...I'm not really a fan of the character - he exists as an attempt, I think, to capitalize on the popularity of Marvel Comics villain like Venom and Carnage, although, ironically, it's still the Joker that's going to sell the movie tickets.
Anyway, what makes The-Batman-Who-Laughs interesting to me, is that his backstory makes for a convincing argument for why Batman would disappear from Gotham for a considerable amount of time - he's running away, trying and failing to find a cure for his monstrous transformation. And now that he's failed, he's coming back to take back Gotham..in the worst ways imaginable.
NOW you have an opportunity to have Batwoman face a truly challenging opponent that probably won't appear in the movies and they can get away with in the CW "Arrowverse" because they already established the presence of a multiverse in their continuity. You can also get away with a recast, because you need an actor who can convincingly play a new take on Batman - a Batman who has embraced the identity of his worst enemy. The World's Greatest Detective wants to act like Hannibal Lector...wouldn't that raise the bar for Kate to show what she could do, eh?
I don't know if Greg Berlanti is willing to roll the dice like that for a time slot that used to be owned by Murder, She Wrote on family-friendly Sunday nights but it would be something..
