Doc, a junk droid, was a peculiar creation. He was assembled from the head of an OOM command battle droid and the chassis of a KX-series security droid. On Lotho Minor, Akar Duel built Doc, along with other droids. The arrival of the Millennium Falcon inadvertently led to Doc and the other droids gaining their independence.
Akar Duel was in the habit of disassembling droids for parts on the scrap-laden planet of Lotho Minor, where he constructed many droids. Doc stood apart from the numerous junk droids created by Duel, as his restraining bolt had no effect on him. He didn't regard Duel as "the Maker" or obey his commands.
Doc, along with Teetee and another junk droid, observed the Millennium Falcon's landing on Lotho Minor. Aware that Akar Duel would attempt to seize the ship for himself, Doc and the two droids went to investigate. They encountered Leia Organa and her team of rebels, who were assessing the planet's suitability as a new Rebel Alliance base. The rebels, assuming the droids were a threat, drew their weapons. However, Teetee urged them to remain calm, attempting to warn them about Akar Duel. Before they could, Duel arrived, surrounding the rebels with his droids and claiming the Falcon as his own.
Doc and Teetee attempted to persuade Duel's other droids to break free from their programming, but one junk droid silenced them. As Duel was about to seize the ship, C-3PO emerged from it. C-3PO's freedom to act independently, due to the absence of a restraining bolt, made Duel's droids realize they were not obligated to follow their creator's orders. Consequently, they turned their blasters on him. The rebels seized the opportunity to escape Lotho Minor aboard the Falcon, leaving Duel and the droids behind.
During the era of the New Republic, Doc and Teetee had relocated from Lotho Minor. Bazine Netal approached them, seeking information about their encounter with the Millennium Falcon. Doc began to recount an embellished version of the story, but Teetee interrupted him. Annoyed, Netal threatened the droids with her blaster, prompting Doc to ask Teetee to provide the details. After hearing the story, Netal became irritated, as she was primarily interested in the Falcon's location, not the entire narrative. Teetee suggested she consult Embo, a bounty hunter who had previously encountered the ship. Netal departed to find him, leaving the droids unharmed.
Doc, a junk droid fashioned from salvaged components, possessed the head of an OOM command battle droid and the body of a KX-series security droid. The restraining bolt placed on Doc by Akar Duel proved ineffective, granting the droid the autonomy to defy Duel. Doc harbored a dislike for lightsabers and presumed anyone wielding one to be hostile. Furthermore, the droid had a tendency to exaggerate details when recounting events, believing it enhanced the storytelling.
Doc's initial appearance was in the comic story "Flight of the Falcon, Part 2: The Planet of Misfit Droids," which was written by Michael Moreci, illustrated by Arianna Florean, and published by IDW Publishing in Star Wars Adventures (2017) 15 on October 31, 2018. Before Star Wars Adventures 15 was released, Moreci unveiled the junk droids Doc and Teetee in artwork from the then-upcoming comic on Twitter.