Edward Nygma of Earth-43 was, like in many realities, the villain The Riddler and an adversary of Batman, who had become a vampire.
The full details of Riddler's earlier history are unknown, but it would appear that he and Batman had fought before, the Riddler's crimes at the time consisting of simple robberies or extortion scams.
Some time after Batman's 'disappearance', the Riddler adopts a more brutal M.O.; while still using his riddles, his crimes escalate from theft and blackmail to drugs and murder, to the point where he uses the body of a murdered Gotham University student to store heroin, shooting the mortician who was about to autopsy the victim. Before he can start to cut open the corpse, however, the now-vampire Batman appears, grimly noting how the Riddler has changed in his absence even as his riddles remain the same (Riddler's last riddle posted to the police department had been ""When Genius becomes dope plus 'E' how does she redeem herself?" Answer: By turning 'Heroine' which minus the E is 'Heroin', lots of it, and redeemable for lots of cash).
Riddler, terrified at his foe's new appearance, attempts to shoot Batman, only to witness the bullets having no effect on the vampire. When he asks Batman what his enemy has become, Batman simply states that he is "The answer to life's every riddle; death and hungry darkness", as he tears the Riddler's throat open with his teeth, drinking his blood as the Riddler screams. The specific details of his death are not revealed, but it is presumed that Batman subsequently cut off Riddler's head to prevent him coming back as another vampire.
Like many of Batman's foes in this dark reality, the Riddler's appearance was far more brutal than in canon; under unspecified circusmtances, he had acquired a large, question mark-shaped scar on his face, another such scar being on his chest with his navel being the dot.