Black Mask has put a bounty on Batman's head. Deathstroke, Bane, Copperhed, Deadshot, and others are going for his head. I'm not sure how The Joker and The Mad Hatter will fix into all of this. But still, when you've got so many gunning for his head wanting that $$$, you're more than likely going to end up with a situation like this:
Deathstroke: I saw him first!
Bane: fukk what you saw first! He's mine!
Copperhead: Hey can I join?
Deadshot:
Who the fukk are you?
Bane:
No! Get the fukk out of here.
Joker: *kicks in the door* FOOD FIGHT!
Deathstroke:
Mad Hatter: *sitting in a corner, sipping tea, oblivious to everything* Dat Alice! Dat sweet, sweet Alice....
So, of course, Batman and Robin have got to step in and stop this fukkery before innocent lives are taken.
Makes sense.