New york underground construction worker Mac Garrity was exposed to radioactive material after a barrel full of an unspecified radioactive chemicals fell on him, mutating him into a human rat known as Griz.
Major Story Arcs
Wolverine: The Best There Is: Contagion
For more information see: Contagion
Wolverine was drunk on a gallon of Everclear when he was shanghaied by some hillbilly underground mutant fighting ring promoters. They shocked Wolverine and threw him into a fight with Griz, who came out from New York to make a name for himself in the ring. Wolverine took a small beating, due to the fact he was still drunk, then popped his claws and cut off Griz's head. Assuming Griz was dead, Wolverine went berserk on the hillbillies that shanghaied him. Unknown to Wolverine, Griz's rat reassembled his body and slinked back into the sewer.
Wolverine: The Best There Is: Broken Quarantine
For more Information See: Broken Quarantine
Griz is seen in a flashback, and it is revealed Contagion staged the hillbilly fighting arena to pull Wolverine out.
Superhuman strength and durability and mental control of rats. Griz also has astounding regenerative powers. His rats were able to reassemble his body after it had been shredded by industrial gears. His rats also reattached his head after Wolverine cut it off. He was able to hold Wolverine (300 lbs) off the ground with one hand at arms length while simultaneously applying enough grip strength to crush his throat.