Durg was a Markalian mercenary, employed by the Kobliad murderer Rao Vantika.
Durg and Quark had a business relationship. Quark had paid Durg for a life-threatening job completed on Vener VII and had Durg released from a Cardassian jail.
In 2369, he and his two Bajoran assistants were sent to Deep Space 9 to intercept and steal a shipment of deuridium. He met with Quark on the station to receive information on the shipment, only to find that Kobliad security officer Ty Kajada was spying on them, when she fell off the third level.
He attacked and boarded the Norkova, firing at the crew. After Vantika (as personified in Julian Bashir) had found his work unsatisfactory, he killed Durg. (DS9: "The Passenger")