A heavyset, barrel-chested Sullustan, Mister Borkus is the proprietor of a no-frills diner in Pons Ora, a small settlement on the mostly unknown world of Abafar. The opportunistic Borkus stumbled upon a clone commando suffering from amnesia. The soldier had escaped a devastating battle, and was stripped of his memory and his identity. Borkus callously took the clone -- Gregor -- under his care, never revealing his origin to the grateful survivor. Borkus "generously" offered to give Gregor room and board, at an expense, and also employed him as a dishwasher. But Gregor's meager wage wasn't enough to pay for his necessities, and thus the lowly dishwasher was little more than Borkus's slave.
Gregor had his memories jogged by the arrival of a Republic special mission team. He confronted Borkus, who was hostile and rejected Gregor's demands for freedom. Borkus thought little of Gregor or his potential.
It was Colonel Gascon -- leader of the intrepid D-Squad -- who rekindled the fire of duty and service in Gregor. Gascon was stranded on Abafar and needed help to continue his crucial mission.
R2-D2, the most battle-seasoned of the droids in D-Squad, led the charge against Borkus when the diner owner refused to release Gregor from servitude. The four astromechs swarmed Borkus, tying him up with their utility cords so Gregor could escape with his recovered armor.
Abafar is remote and unremarkable, save for its rich deposits of the explosive Rhydonium. Borkus kept his enormous ears open for strange activity on the planet, and new the Separatists conspired to use Rhydonium in a plot to sabotage a Republic target.