Dirtnap was a mutant with the ability to absorb living beings and take on their forms. He first encountered Wolverine when he absorbed a young boy, and he then attempted to absorb Wolverine, but couldn't due to Wolverine's healing factor. He escaped from Wolverine by absorbing a rat and taking on its form.
He later encountered Wolverine again when he was a member of Genesis' Dark Riders. They were attempting to bond the adamantium from Cyber onto Wolverine's skeleton after it had been removed by Magneto. The procedure failed — Wolverine's body, which now had a stronger healing factor than ever, violently rejected the metal — and sent him into a feral state, killing everyone who had not died from the metallic shards. However, Dirtnap was lucky enough to survive.
He later stalked Wolverine with the help of Chimera to exact revenge on the feral X-Man. Dirtnap earned the enmity of the symbiotic Venom when he absorbed the female symbiote named Scream. Venom managed to free the people Dirtnap had absorbed, including Scream, a young boy and Federal agent Darryl Banks. Dirtnap was then seemingly killed in an implosion along with Chimera.
When Chimera returned and attacked Generation X with her new-found ally, Emplate, Dirtnap accompanied them. Emplate went to visit his unconscious sisters in the infirmary and they awoke when they sensed his presence. Wanting to help their brother, the twins merged bodies with him, creating the amalgamated form of M-Plate. M-Plate—far from being a good being—now had a ferocious plan to destroy the universe. However, in the rush to get on with their plan of merging the universe into a single consciousness, Dirtnap was left behind. After the Generation X kids treated him well for perhaps the first time in his life, he started to rethink his alliances. When M-Plate tried to turn on the Universal Amalgamator, Dirtnap, realizing the threat to his new found friends, jumped on M-Plate and swallowed the being whole. Unfortunately, the entity was too much for Dirtnap to handle, and he exploded, but not before disassociating M-Plate into its constituent parts of Emplate and M.
Originally, Dirtnap had a human form. He would still absorb bodies into his own and take over their form, evident by a gray t-shirt with a red smiley face that would appear on the victims. However, in trying to flee from Wolverine he absorbed a rat and took on its form permanently, the smiley face now being on his back. He still retained his powers, but the rat became his default form.