Grinner served as one of the Cavrilhu Pirates, reporting to the pirate chief Zothip. His duty was to safeguard the Kauron asteroid station.
Along with Crans, Portin, Control, and the aforementioned Zothip, Grinner infiltrated the living space of Moff Vilim Disra aboard the Imperial Capital ship stationed above Bastion. Unbeknownst to Grinner, the Mistryl Shadow Guard, specifically Karoly D'ulin, was tracking their movements. Inside Disra's quarters, Karoly assassinated Zothip. Following the demise of Zothip, Control assumed command of the Cavrilhu Pirates.