The Rabid Robins are the minions of the evil Batman Who Laughs from Earth-22 of the Dark Multiverse.  In that reality, the Earth -22 Joker learns of Batman‘s identity as Bruce Wayne and subjects thousands of Gotham City’s citizens to the chemicals that transformed Batman into a new fusion of Batman and the Joker, one with Bruce Wayne’s intelligence and physical strength and the Joker’s psychopathy and warped, sadistic sense of humor. The process proves irreversible by the time Batman discovers what is happening to him. The Batman Who Laughs proceeds to take over Earth-22, killing off most of his allies and recruiting the children infected by the Joker Toxin as his “Rabid Robins“.