Dexa was a Talaxian woman who, along with five hundred other Talaxians, took refuge on an asteroid colony that they turned into their home. She had a son named Brax and was widowed. She had an uncle named Neelix.
In 2378, a shuttle carrying Neelix crashed due to an explosion. Dexa tended to Neelix's injuries and explained that the explosion was caused by a group of miners who wanted the Talaxians to leave their new home. Dexa was, at first, wary of Neelix, wondering why he lived with aliens, so she kept him locked behind a force field. Dexa brought the Talaxian council regent Oxilon to meet Neelix, and he was set free. Dexa told him about the Talaxians who lived inside the asteroid, which they developed using technology from their disassembled ships. Dexa also informed him that they were being threatened by miners who wished them to leave so they could have the mineral resources of the asteroid.
Before Neelix left, he discovered that Dexa's son, Brax, had stowed away on the Delta Flyer. When he returned the boy to Dexa he found her in a confrontation with the miners. Nocona, head of the miners, ordered the Talaxians to evacuate the asteroid so it could be demolished. Dexa stood up to the miners and they pushed her aside. Neelix defended her and her son, forcing the miners to leave temporarily. Dexa wanted to defend her home, and finally persuaded the council to accept Neelix's and USS Voyager's help. Dexa accompanied Neelix to Voyager to discuss the situation with Captain Janeway. Dexa and Neelix became romantically involved and while working on preparations for their defense, engaged in a passionate kiss. With the assistance of Neelix, the Talaxian settlers were able to resist the miners and save their home.
Neelix, having fallen in love with Dexa, elected to stay behind with her while Voyager continued towards Earth. A few weeks later, Neelix told Seven of Nine (via subspace communications) that he was thinking of asking Dexa to marry him, a move Seven approved of. (VOY: "Homestead", "Endgame")