The past of Vermin and his partner Agent Crock was unknown, but what is known is that they formerly worked for S.H.I.E.L.D. before being forced to live in the sewers of New York City following the organization's dissolution. Crock himself was a Super-Soldier created by S.H.I.E.L.D. They ruled over the sewers with an iron fist. Vermin unexpectedly encountered the Young Ultimates while they were in search of gang leader Crossbones in the sewers. The Ultimates fought off Vermin, forcing him to retreat. The Ultimates were later joined by NYPD Detective Terry Schreck and encountered both Vermin and Agent Crock who possessed a psychic connection with one another. Unable to reason with the pair, Shadowcat phased herself through Crock's head, killing him and Vermin in turn due to their mental link.