Shortly after the Naboo crisis, Trang Robotics created a line of high performance battle droids for mysterious private investors who allegedly wanted units capable of more complex tactical operation than the standard B1 battle droids. GX1-07 was made as a qualification test unit prior to the full roll out of the GX1 line when bugs were still being worked out and design features were being finalized. This meant that GX1-07 had his cognitive module altered by engineers at Trang during proving trials in order to resolve issues and meet certain performance metrics.

After the completion of the proving trials, GX1-07 was slated to become a demonstration model who could be used to show off the capabilities of the GX1 models to future customers. On the way back to the Trang labs after one such demonstration tour, GX1-07 was 'radicalized' by the maintenance astromech assigned to repair and tune its systems in between outings. R3-A6 claimed to be a secret agent from something called the 'droid underground' sent to help liberate enslaved droids from the Trang Robotics labs.

A more sophisticated droid, like a protocol unit, might have taken these claims with a grain of salt and considered that they might be the ravings of an eccentric maintenance droid badly in need of a memory wipe, but GX1-07 was completely sold. The astromech took to calling GX1-07 'Thumper' instead of his alpha-numeric designation and eventually helped him plot his escape. On their next mission together, R3-A4 loaded Thumper into an escape pod and jettisoned him from the ship while the ship was in hyperspace. By the time the crew was able to safely drop out of hyperspace, turn around, and come back, the escape pod had been picked up by a Hutt junk collector and Thumper was on his way to 'freedom'.

The good news was that Thumper was now out of the control of Trang Robotics and even the rough and tumble crew of the Hutt junk ship wasn't willing to mess with a 7 foot tall battle droid asserting its independence. The bad news was that Thumper's astromech friend hadn't really prepared him for a life of freedom. Thumper took to watching other sentient species and copying their behavior and with the examples presented to him in Hutt space, he quickly determined that the 'normal' thing to do was to seek gainful employment in a field that best fit one's particular set of skills.

And that is how Thumper ended up serving on the Sovereign Star with an employment contract that stipulates an indefinite period of servitude in exchange for what amounts to just enough to cover parts and ammo...