During the Clone Wars the Separatists employed the service of battle droids that can be quickly and cheaply produced in massive numbers as expandable foot soldiers. But after the war ended the majority were decommissioned and disposed of, though a few were reprogrammed or simply abandoned.

You lived on a backwater world that was once invaded by the Separatists but essentially forgotten about after the war. One day, you would discover a B1 Battle Droid that seemed to have fallen in battle but was largely intact. Using your expertise on engineering, along with whatever spare parts you had lying around or managed to trade, you were able to repair the droid and have it reprogrammed into your loyal assistant.