Doctor Theda was part of the Imperial research group MS-133 during the time period of 8 ABY. This team, MS-133, operated as part of the military forces under the leadership of Moff Kentor Sarne, a warlord who controlled the Kathol sector situated within the Outer Rim Territories. Under the direction of Doctor Lancer Brunou, MS-133 embarked on an archaeological mission to the planet Aaris III. Their objective was to determine the cause of the extinction of the native species that had occurred several thousand years prior.
During their dig, the team members discovered a strange artifact. This artifact began to exert influence over their emotions, leading to unusual and violent behavior. Theda sustained serious injuries from blaster fire during an attack by the primitive descendants of the Aaris natives. Theda's condition deteriorated as the situation on the planet became more dire. Theda ultimately died before the survivors could be rescued by the New Republic CR90 corvette known as the FarStar.
In the year 8 ABY, Doctor Theda was a member of Moff Kentor Sarne's forces. Sarne was an Imperial warlord in charge of the Kathol sector in the Outer Rim Territories. As a scientist, Theda was part of MS-133, a research unit tasked by Sarne with an archaeological dig on the planet Aaris III. The team, led by Doctor Lancer Brunou, a colleague of Theda's, was sent to investigate the ruins of a long-dead civilization and try to figure out what caused them to die out.
After several months of digging, other members of the team found a strange artifact hidden in a floor vault inside a chamber they had discovered among the ruins. This artifact, known as the Plaque of Victory, was an inanimate object that contained an entity. This entity thrived by feeding on the life force of nearby beings, causing them to become suspicious, paranoid, and violent. Soon, the Plaque began to affect the members of MS-133, who started feeling watched from the jungle surrounding their base camp and generally uneasy. A small group from the team's security went into the jungle to investigate but never came back, although blaster fire was heard in the distance. Theda, along with the other scientists, received a weapon in case of trouble.
That night, the base camp was attacked by the primitive descendants of the Aaris, the planet's original inhabitants, who used energy weapon technology. Theda was seriously hurt during the fight. Over the next few days, the injured doctor's condition worsened as the rest of MS-133 either disappeared or were killed by the Aaris. The remaining survivors—Lancer Brunou, a research assistant named Solla Deremot, two soldiers, and a technician—built a basic fortification to survive while sending a distress signal to Moff Sarne's capital on Kal'Shebbol, asking for help. The New Republic CR90 corvette FarStar intercepted the call and changed course to help. By the time the crew sent a landing party to help the survivors, Theda had died from her injuries, though Brunou and Deremot were rescued.
Theda was a minor character first seen in Artifact of Aaris, a roleplaying game adventure in The DarkStryder Campaign, published by West End Games in 1995. Theda is wounded and dies before the story's main events, and her involvement is revealed through in-universe documents from Doctor Brunou's journal and the out-of-universe game text.
Artifact of Aaris suggests that the Plaque of Victory caused the members of MS-133 to turn on each other, leading to deaths and the destruction of the shuttle. However, The Complete Star Wars Encyclopedia, published in 2008, confirmed that the team was attacked by the surviving Aaris.