Massad Thrumble, an Imperial droid researcher who achieved the rank of Admiral, worked for Simonelle. He successfully engineered fully functional human replica droids for entities like Black Sun and the Empire. Among his creations were Guri, as well as duplicates of Frija Torlock and her father, Lexhannen.
Early in his career, Massad Thrumble served the Empire as a Captain within a droid manufacturing facility. He eventually advanced to the position of Admiral, overseeing the research facility where he contributed to the development of Human replica droids, including Guri.
Thrumble later retired and, by 4 ABY, he was the proprietor of a small cantina located on Hurd's Moon. He possessed a customized medical droid named A-OIC, also referred to as Doc. Doc was stolen by the Pikkel Sisters for Spinda Caveel of Murninkam. Shortly after this incident, Guri sought him out, desiring to be reprogrammed. Thrumble considered this a more appealing challenge than monetary gain, but informed Guri that he could only accomplish the task with Doc's assistance. Soon after, he was approached by Kar Yang, a bounty hunter hired by Savan, niece of Prince Xizor, to capture Guri. Thrumble initially feigned ignorance, and his henchmen moved to confront the intruder; however, witnessing the Hiitian's power, Thrumble directed him toward Murninkam.
Guri succeeded and returned to Thrumble from Murninkam with the droid. Thrumble cautioned her that the procedure could be fatal or result in significant changes, but Guri remained determined. However, she was being pursued. Yang interrupted Thrumble before he could commence the operation on Guri, and demanded that she neutralize Thrumble in order to follow him; but Guri fought and killed him. Thrumble did some recalibrations while Doc removed and disposed Yang's body.
Following the incident, Thrumble enhanced the automated defenses of his protected area, and despite subsequent attempts by other groups to reach Guri, they proved unsuccessful, as Skahtul reported to Savan. The procedure resumed, with Doc warning about the potential for damage to her neurocortex. Later, the droid reported success with the progress of the binhex sequence, but Thrumble cautioned that her brain's complexity made a successful outcome uncertain.
Three additional groups journeyed to Hurd's Moon. The first consisted of Caveel and the Pikkel Sisters, seeking to reclaim Doc. The second was Savan, and the third was the Heroes of Yavin, who were tracking Savan. All of this occurred while he and Doc performed the operation to remove Guri's memories.
Thrumble's defenses successfully repelled Savan and her mercenaries, leading him to realize that someone was still pursuing her. With Guri's past erased, Thrumble escorted her to another room and attempted to escape with her. In a security room, Thrumble saw the Pike Sisters (whom Guri had forgotten) and the famous Heroes of Yavin, and told Guri they were all probably after her.
Guri assured him of her ability to pilot her ship, the Stinger, and en route, she experienced a sudden headache, prompting Thrumble to assist her in walking. They were spotted by Prevaro, Savan's lieutenant, who directed their mercenaries to attack. However, Guri remembered her fighting abilities and defeated the thugs. They then encountered Savan herself, who attempted to control Guri using a code phrase she had learned from Xizor. Savan ordered Guri to kill Thrumble, but the code phrase did not work, and she instead punched and threw her down.
Later, Thrumble explained to Luke Skywalker that the negative aspects of her memory were wiped, and they allowed her to depart in peace.