Slick was the nickname of a clone trooper sergeant who fought in the Battle of Christophsis. While loyal to the Republic, Slick felt the Jedi were keeping his fellow clone troopers enslaved to do their bidding in the line of fire, for which reason he discretely worked for Asajj Ventress. Following a mission on Christophsis, he returned to the Republic base, and informed Ventress of the Republic's plan.
The droid army ambushed the Republic forces, and Kenobi and Skywalker quickly realised that there was a traitor in their midst. While they went to search for information in Confederacy-held territory, they ordered Clone Captain Rex and Commander Cody to stay and find Republic traitor. In the following interrogation of Slick's men, Slick was revealed to be the Confederate spy. After he severely damaged the Republic base's weapons depot, Rex and Cody engaged him in a brawl. Slick was apprehended, and when Skywalker and Kenobi returned, the traitorous clone was taken to lock-up.