When Ballard entered Starfleet Academy, she became close friends with Harry Kim, who lived across the hall in their student dorm. She taught him to ice skate, despite his dislike for cold weather. During her Academy years, she never knew that Harry had a crush on her, and that being in the same classes as him was not a coincidence. Her favorite things to eat were peanut butter and jelly sandwiches; during dinner with Captain Kathryn Janeway she mentioned that she used to live on them during her Academy years. Her sloppiness sometimes caused Kim to ask for a baryon sweep of his room.
In 2371, Ballard graduated from Starfleet Academy as an Ensign, and was posted to the newly commissioned USS Voyager, under the command of Captain Janeway. There, she was reunited with Harry Kim. Her primary post was in main engineering.
In 2374, Harry and Lyndsay were assigned to an away mission on a Class-M planet in the Vyntadi Expanse to investigate readings of dilithium ore. However, it was a trap by a Hirogen hunting party, who had reconfigured a power cell to give a false dilithium signal. During their retreat to the shuttle, Ballard was hit by an neural disruptor and died on the way back to Voyager. Harry Kim gave the eulogy and she was buried in space.
- See also: Jhet'leya.
Unknown to the Voyager crew, Ballard's body was recovered by the Kobali, who re-animated her as one of their own, named Jhet'leya. In 2376, she returned to Voyager and attempted to resume her life as Ballard. However, she discovered after a short time that her mind and body were no longer Human. During her time away, she made a list of the things she wanted to do if she ever returned to Voyager. Eating Jibelian berry salad was #6, dazzling B'Elanna Torres was #16, hearing Harry play his music was #26, showing up for duty shifts on time was #27, and make Tuvok laugh was #32.
Ballard's favorite saying came from an old Klingon battle cry, "Own the day." She believed in attacking each day and possessing it. According to Kim, that's what made her so much fun to be around.
She eventually returned to the Kobali when Voyager was being attacked by them, demanding she return. She came to realize that she didn't belong on Voyager anymore, and made the decision herself to go back. (VOY: "Ashes to Ashes")
Ensign Ballard's original "death" was not shown on screen or mentioned in an episode around the time it happened, only in this episode. Ballard mentions a date of death as stardate 51563, this would have placed it between the episodes "Hunters" and "Prey", from 2374 in Season 4. Though when unpacking with Harry, she mentions being gone for three years – leaving a year of death in 2373. The story she originally tells Captain Janeway, including 6 months of travel in a shuttlecraft, adds up to approximately 2.5 years – both of these are before the crew met the Hirogen for the first time.
It is possible Ensign Ballard was originally meant to be Ahni Jetal of "Latent Image", as they both died around the same time, both on shuttle accidents, both of alien neural disruptor-weapons, and both with Harry Kim.
To date, Lyndsay Ballard is one of two Starfleet Officers to be re-animated after a lengthy post-mortem (the other being Spock). Picard, Worf, Neelix, O'Brien, and Harry Kim have all died, but have all been brought back to life within 24 hours of their death or been replaced by their alternate time/universe duplicates.