A villain and member of U.N.I.C.O.R.N. Yellow Jacket first encountered Critter after she first joined The Core. Operating with Rookie, Critter almost took Yellow Jacket down. However, he traded as many bruises as he gave, cutting Critters shoulder open and eventually hospitalizing her, despite her and Rookie defeating him.

In the excitement of getting Critter to a hospital, Yellow Jacket seemingly got away.

While the rest of The Core were fighting against the Ampibodons controlled by Tidepool, Icon and Starlette confronted Yellow Jacket and his agents of U.N.I.C.O.R.N., they were held back by Cricket until Rookie managed to disrupt her powers allowing the rest of the group to defeat the villain group.