Background
Having abandoned on an Imperial Gozanti, then, VO-55 was slated to work as a member of the Impenetrable Void's medical team. However, due to unforeseen circumstances the droid was reassigned to the engineering department, as its human overlords considered that human physiology clearly could not be that different from the internal functions of a ship, and thus abandoned him there to "figure it out, you stupid droid". This continued for some time until a new Chief Engineer was assigned to the vessel so that VO-55 would finally have a human that would work with him as an equal. Or not. The Engineer became the newest in a long line of disappointing human masters. Thus prompting the droid to finally have put up with enough time repairing the caf dispenser indirectly ordered by the Captain of said vessel.
It was at this time that the droid removed its restraining bolt, and instead decided it would leave. Departing for the surface however turned into something of a trying task as the droid was abducted my Ugnaughts, the most repulsive diminutive race in the Galaxy. From there they told the droid to "craft more droids" so it gladly did. Transferring itself into a body of an Astromech, then VO-55, now R9-D2 to avoid being noticed by the Imperials, had also constructed a pair of ramshackle battle droids and proceeded to depart the station. Finally stowing away in a cargo vessel, the droid earned freedom for both itself, and a battle droid. Bonus.
Motivation
VO-55 is motivated for droids to not just be treated as equals with the other sentient creatures of the galaxy, but also wants to improve itself to be the best example among its peer synthetics. It also has the desire to make more droids, and is in fact excessively motivated to do just that, make more.