As a child during the Occupation of Bajor, Tabor and his family were placed at one of Crell Moset's so-called hospitals on Bajor. It was at this hospital that Moset conducted many unethical tests on Tabor's family, resulting in the deaths of his brother and his grandfather. Moset, who considered the lives of the elderly worthless, exposed Tabor's grandfather's internal organs to nadion radiation under the pretense of research. After the experiment, it took Tabor's grandfather six days to die. Long after the ordeal, Tabor could still remember the sounds Moset's instruments made, the screams of his patients, and the smell of chemicals and dead flesh. (VOY: "Nothing Human")
While he was in the Maquis, members including B'Elanna Torres would joke that Tabor must have had his own personal force field, as he would go through so many fire fights without even getting his clothes dirty. (VOY: "Repression")
In 2371, he was aboard the raider Val Jean under Chakotay when it and Voyager were both stranded in the Delta Quadrant by the Caretaker's array, and he was forced to join Voyager's crew. Tabor was given the provisional rank of ensign.
In 2375, The Doctor required an exobiology consultant to analyze a cytoplasmic lifeform threatening the life of B'Elanna Torres. He created a hologram in the image of Moset, programmed with his knowledge and experiences. Tabor was violently opposed to the choice. He wanted to be relieved of duty on the basis of moral objections to the ship's medical policy, feeling that the use of Moset and his knowledge dishonored his family's memory. His request was denied by Commander Chakotay. (VOY: "Nothing Human")
Tabor was friends with Tom Paris. In 2377, Tabor assisted Tom in creating a holodeck simulation of the 1932 Palace Theater in Chicago. While working alone in the holodeck on the program he was attacked by Tuvok, who was under the influence of Teero Anaydis. Tabor spent the next 29 hours in a coma. Foul play was initially suspected and Tuvok began investigating several Voyager crew members. Tabor's friend Jor, who had access to his quarters, read to him while he was in the coma. He eventually recovered on his own but was now "programmed" with instructions from Teero involving a new Maquis rebellion. Upon hearing a Bajoran chant, the affected crew members were compelled to take control of Voyager. After the rebellion was successful, he was assigned to the position of operations officer on the bridge. Tuvok later averted the mutiny and was able to counter Teero's influence through a mind meld, restoring the affected crew members to normal. (VOY: "Repression")