TD-D9 was a droid with multiple red Photoreceptors and six spider-like legs who essentially raised a young Maul and aided him in his early training and education in a facility on the volcanic world of Mustafar.
Maul hated the droid and his harsh nature, as the droid would subject Maul to harsh training methods, but would later value him as a friend. One brutal training method required Maul to memorize star systems and planets, and failure to complete it in a set time resulted in an electric shock. One day, the droid took Maul out of his room, and eventually started to chase the Zabrak. Maul ran into a hallway and into a private room, which belonged to Dark Lord of the Sith Darth Sidious. The droid was damaged, and when the droid entered the room where Sidious and Maul were talking, he was ordered away where he would fix himself.
The droid would continue to supervise Maul's training throughout the years. At one point, Maul used the Force on a staff, and TD-D9 hurried to inform Lord Sidious who was quite pleased with the result. He would then take Maul to Tosste where he would train him to harness the Force. A short time later, the droid lowered and tied a upside down Maul to a vat of acid. Maul would attempt to break free while Sidious gave him a history of the Sith. Sidious, displeased with the time Maul took to break free, had the droid make Maul repeat the challenge, but would lower him much quicker.
Soon, Maul would see a softer side of the droid, when he apologized for accidentally breaking his ribs during a training session, and even expressed some form of humor, by imitating Darth Sidious's voice, and warmth by telling Maul to call him by Deenine. Maul soon began to think of the droid as his friend, who lied to Sidious saying that he lied to Maul about the rib breaking being an accident, when it in fact was an accident; only saying that as to not incur Sidious's wrath.
Maul would be given a large room, and one day the droid noticed Maul had drawn an image of Mustafar on the wall. The droid cautioned Maul and told him to get rid of it before Sidious could find it, however, Sidious did, and he summoned Maul. When arrived, Sidious spoke with Maul and kept the droid nearby. On Sidious's command, TD-D9 activated a lever which plunged Maul to the terrain of the volcanic world.
- Restraint (First mentioned) (Indirect mention only)
- The Wrath of Darth Maul (First appearance) (First identified as TD-D9) (Appears in flashback(s))