Joker kills Jason in 1987 with the crowbar/explosive in the warehouse.
The Joker managing to flood Gotham with the toxin he fell into.
OR
Huntress gets pushed away so much that she retreats to a life of crime.
OR
When Batman, Oracle, Nightwing, Batgirl, and Huntress are trapped......Somewhere and cut off from any supplies, they decide to eat Oracle's legs when they begin to starve. With or without her consent I'll leave up to you.
