In 2371, while Starfleet was trying to capture the Maquis raider Val Jean in the Badlands, she and the rest of her Maquis crew were pulled 70,000 light years across the galaxy, deep into the Delta Quadrant by the Caretaker's array and forced to merge with the crew of the Voyager during its seven-year journey home. Before serving as Voyager's chief engineer, B'Elanna had joined the Maquis right after dropping out of the Academy after years of disciplinary issues.
Since the two crews were stranded together in the Delta Quadrant, they were forced to work together as a single crew. Torres was initially assigned the provisional rank of lieutenant junior grade. Torres had difficulty getting along with the temporary chief engineer, Joe Carey. She was recommended as a replacement chief engineer by Chakotay. However, Kathryn Janeway opposed this decision. After Voyager became trapped in a quantum singularity, Torres proved her skills to Janeway and earned her respect. Janeway then gave Torres the provisional rank of full lieutenant (giving her rank parity with Carey) and made her chief engineer over Carey.
Torres wed Tom Paris after an interstellar starship race that Irina, one of the participants, tried to sabotage and thereby destroy the peace in the area. She had joined Paris in the race because she wished to share his interests. A bomb was planted on their ship, but they were able to eject it in time. They married after the race.
During the final battle with the Borg which led to Voyager's return home, Torres gave birth to her daughter, Miral Paris, named for B'Elanna's mother.