Doctor, a heavily modified T-series tactical droid, was put into service by Magistrate Passel Argente to fight for the Confederacy of Independent Systems during the Clone Wars. This droid, arrogant and belittling, operated from a facility located on Moorja. There, he conceived Project Instinction, a Separatist plan designed to make the agricultural world of Ukio unusable by the Galactic Republic. Doctor's scheme involved gathering the light-sensitive, electromagnetic soil of Moorja and spreading it across Ukio's well-known planetary shield, thereby creating a constant darkness that would halt crop production. The droid predicted the Ukians would be compelled to disable their shield to clear the soil cloud, an action that would permit him to deploy forces onto the planet's surface. Subsequently, devices would be activated to transmit signals that would induce madness in the planet's inhabitants, leading them to destroy their own crops.
Doctor, confident in the infallibility of his strategy, initiated Project Instinction. He loaded the soil onto altered seismic tanks and transported them to Ukio aboard a Lucrehulk-class battleship. He encountered minimal Republic resistance in space, and as expected, the Ukians deactivated their planetary shield, allowing Doctor to proceed to the next phase of his plan with relative ease. However, while Doctor's devices were successfully driving the Ukians insane, the Confederacy suffered a setback when their positions were overwhelmed by the Jedi Padawan Tyzen Xebec. The Padawan ultimately destroyed Doctor's devices. Although the tactical droid managed to corner the young Jedi, he was ultimately destroyed by Jedi General Keelyvine Reus.
During the Clone Wars, the Confederacy of Independent Systems was served by a modified T-series tactical droid known as "Doctor." He operated under the command of Magistrate Passel Argente of the Corporate Alliance, who had personally commissioned the droid's creation, a fact Doctor was well aware of. Doctor also had a pet, named Seventeen, a non-sentient being constructed from various animal parts, including the cannok, the blarth, and the boma. Doctor's command center was located at a base on the world of Moorja, a place plagued by ion storms. It was there that he had an array of modified seismic tanks collecting Moorjan soil for future use. Argente visited him at the Confederate base to discuss their plans to seize the crucial agriworld of Ukio for the Confederacy. While Argente was eager to launch an immediate assault, Doctor insisted on a cautious and patient approach to ensure the success of their operation.
Doctor had devised a plan he called Project Instinction. The initial phase involved deploying modified seismic tanks, filled with Moorjan soil, from a single battleship just above Ukio's renowned planetary shield. The Moorjan soil's electromagnetic and photosensitive properties would cause it to instantly adhere to the shield and spread across it as Ukio orbited its sun. This would effectively create a perpetual eclipse, severely impacting Ukio's sensitive crop growth. This would significantly harm the Galactic Republic, as Ukio supplied both their troopers and the entire Abrion sector, along with worlds along the Triellus Trade Route. Consequently, the Ukians would be compelled to briefly lower their shields to disperse the soil. The second phase of Project Instinction involved shuttles penetrating the lowered shield and landing on Ukio. Devices would then be deployed to transmit a neural signal across the planet, causing all living beings to act against their natural instincts, plunging the planet into chaos. The native gigauns, in particular, would deviate from their usual paths and trample the sensitive Ukian crops, effectively destroying the world's value and rendering it useless to the Republic.
Doctor had his seismic tanks filled with Moorjan soil, and then loaded on a Lucrehulk-class battleship. He then traveled to Ukio, where he put the first phase of his plan into effect. Although Jedi-piloted Delta-7B Aethersprite-class light interceptors briefly engaged his tanks, they were unable to stem the deployment of the soil. The Republic fleet defending Ukio moved to engage Doctor's battleship, as the Ukians predictably dropped their shields momentarily. Doctor and his assistants made their way to the surface in three Sheathipede-class transport shuttles, and began to deploy the neural devices. Doctor contacted Magistrate Argente directly, and informed him of the progress. The Magistrate was concerned that Doctor was able to contact him in spite of the jamming, but the tactical droid had thought ahead, and was only using frequencies he had not had jammed. Argente then made sure that the devices would not affect Doctor's own troops, but the tactical droid dismissed the idea, although the concept piqued his curiosity. The devices were then deployed, and activated, driving the living beings on Ukio into a rage.
The Project proceeded as planned, as the world was sent into a violent frenzy. The gigauns acted as predicted, destroying the Ukian crops. However, Republic elements on Ukio's surface began to turn the tide when Jedi Padawan Tyzen Xebec and Agricultural Corps member Sanya managed to destroy one of Doctor's devices. Xebec then destroyed another of the devices, before approaching Doctor's position. The Padawan was knocked from his commandeered Single Trooper Aerial Platform by a projectile, but was able to engage Doctor's units. The young Zabrak then decimated the soldiers and destroyed the last Project Instinction device. Doctor picked up a blaster and shot the young Jedi in the shoulder, instantly disarming him. As the tactical droid bore down on his prey, he was decapitated by the Jedi General Keelyvine Reus, who was commanding the Republic task force and had recently arrived on the planet. Reus proceeded to inspect Doctor's remains. Although the Republic was able to tactically thwart Doctor's efforts, he had created a significant amount of economic turbulence on Ukio. Stock prices tumbled, and Magistrate Argente was merely able to purchase the planet, ultimately securing it for the Confederacy.
Doctor held a strong aversion to organic life forms, often questioning their diverse eccentricities. When Magistrate Argente likened the desolate and storm-ridden landscape of Moorja to the Nine Corellian Hells, Doctor dismissed it with scorn, considering such beliefs to be beneath him. Argente retorted by calling Doctor a "man" of science, but Doctor had little regard for that concept either. He believed that science was a flawed, organic construct, tainted by notions like hope, denial, and expectation. Instead, Doctor found solace in numbers, not in terms of profit as he suspected Argente thought, but as variables and probabilities. He was also perplexed by the illogical and unreliable nature of biological clocks, particularly when his pet Seventeen demanded food prematurely.
When planning the assault on Ukio, Doctor cautioned Argente against hasty actions. He argued that with the Confederacy nearing victory, patience was paramount, and thorough preparation was essential to ensure success. Doctor hoped that this approach would allow them to seize Ukio with minimal complications. Upon landing on Ukio, Argente expressed surprise that Doctor could still communicate despite the supposed Confederate jamming. Doctor condescendingly explained the principles of selectively jamming certain frequencies. Doctor was acutely aware of his expertise in tactics, understanding that Argente had commissioned him for that very reason. While he was unimpressed by the Magistrate's limited understanding of his plan, he was intrigued by the possibility of creating similar neurological scramblers that could drive automatons berserk. This concept fascinated Doctor to the point that he dedicated twelve subroutines of his thought processors to its further exploration.
Unlike most T-series droids, Doctor had a circular right photoreceptor that was red. His head also featured several cylindrical protrusions with glowing yellow bands, as well as a larger device attached to the back. His right arm was also significantly different from the standard T-series unit, with a silver appearance instead of the brown plating found on most of his "body." It also featured various functional tools, including a holoprojector. A smaller arm extended from the right side of his torso, which he used to hold Seventeen's leash. In his left arm, Doctor carried a blaster pistol, which he used effectively against the Jedi Padawan Tyzen Xebec.
Doctor debuted in The Clone Wars: Act on Instinct, published in 2009 and written by Pablo Hidalgo. The character was introduced in the fifth issue of the comic, initially drawn by Jeff Carlisle, although other artists later contributed to the comic's illustrations.