“Slick” was the nickname of a Clone Sergeant who served in the Grand Army of the Republic during the Clone Wars. Early in the war, he came to believe that the Jedi Order, which commanded the clone army, was incompetent and using him and his fellow clone troopers as slaves in their war against the Confederacy of Independent Systems. He secretly turned against the interests of the Republic and began to pass information to Asajj Ventress, a Sith acolyte of the Separatist leader Count Dooku. She offered the clone money, but what Slick truly wished for was freedom.
Slick’s duplicity came to light during the Battle of Christophsis, which was an early engagement of the war. He passed information to Ventress regarding the specifics of a Republic operation, which led the clone forces and their Jedi leaders, Generals Obi-Wan Kenobi and Anakin Skywalker, into an ambush. The Jedi and the two clone commanding officers, Clone Commander “Cody” and Clone Captain “Rex,” realized that this meant there was a spy among their ranks.
While the Jedi set off to infiltrate the Separatist headquarters to learn more, Cody and Rex investigated the Republic base. They discovered Slick’s actions once he accidentally let slip that he knew the Jedi had left the Republic base, and Slick led the clone officers on a chase throughout the complex. Once he was captured, Slick berated the Jedi for what he saw as their treatment of his clone brothers, and he was taken into custody on Cody’s orders. Slick’s motives were covered up by the Republic so as to not spread similar sentiments amongst the clone ranks, and the Jedi Order was forced to contend with the reality that clones were not completely obedient.