Marayna was an alien responsible for preserving an inversion nebula in the Delta Quadrant. She worked alone on a hidden space station within the nebula, generating a dampening field to stabilize the nebula so that others from her homeworld may enjoy its beauty. Although she took up the assignment by choice, the monotonous routine and separation from her people made her feel lonely. To amuse herself, she tapped into the computers of unknowing passing ships to observe the details of their crews' lives.
When the USS Voyager encountered the nebula in 2373 and studied it in detail, Marayna tapped into Voyager's system and discovered the holodeck. She created an uplink to the holodeck and appeared as a Human holo-character in Neelix's Paxau Resort holoprogram. From there, she interacted with Voyager's crew members, including giving hydrosailing lessons to Harry Kim and Kes. Harry became infatuated with the Marayna hologram to the point of being distracted while on duty, and asked Tuvok for help in suppressing his emotions.
During a luau organized by Neelix on the holodeck, Tuvok saw the Marayna hologram playing with kal-toh and engaged in a deep conversation with her. Although Tuvok was only intellectually interested in her, Marayna took a romantic interest in him.
When Voyager finished studying the nebula and attempted to leave, Marayna stopped them from leaving by interfering with Voyager's systems. When Harry visited the holodeck on a break from isolating the problem, he was jealous seeing Tuvok playing kal-toh with the Marayna hologram, thinking that Tuvok had taken an interest in her. In the ensuing argument, Tuvok deleted the Marayna hologram. However, when Tuvok returned to his quarters, he found the Marayna hologram there (having transferred herself into sickbay and stolen the mobile emitter), and demonstrated her control over Voyager by silencing the intruder alert alarm.
The crew managed to trace a subspace signal that was interfacing with the ship's computer, and Tuvok transported to the source of the signal. He found himself aboard a space station with the real Marayna. She demanded that Tuvok stay with her or she would destroy Voyager, but eventually consented to let him and Voyager go when Tuvok appealed to her senses by reminding her that he had a wife back on his homeworld and a ship that depended on him, and whatever reason he remained for her would not be the one she wanted. He suggested that she call for a replacement and return to her homeworld to live with her people where she might find someone more suitable. (VOY: "Alter Ego")