Bester (Dax Griffin) was a mechanic operating on an unknown Rim planet in the year 2512. Due to his work there, he'd earned a reputation as a "genius mechanic," a reputation that led to his being hired by Captain Malcolm Reynolds shortly after Reynolds purchased the Firefly-class transport Serenity.
Unfortunately, Bester did not live up to his reputation. Serenity's initial timetable was met with one delay after another when Bester was unable to repair the ship's engines. Reynolds went to confront his mechanic, but walked in on him having sex with a local girl in the engine room. The girl, Kaywinnit Lee Frye, proved to be better with engines than Bester, easily spotting the trouble and recommending a course of action. Impressed, Reynolds offered her a job aboard Serenity, and she eagerly accepted. However, the ship had no need of two mechanics, and Bester found himself out of a job.