Dors Vanabili is a robot who initially is assigned by Chetter Hummin to protect Hari Seldon while Seldon attempts to develop his theory of psychohistory. Their paths intersect at Streeling University, where Dors teaches history. The two fall in love and marry, adopting Raych Seldon as their son. Seldon thinks of Venabili as a human, although given her speed, strength, and intelligence, he suspects that she is a robot. He maintains that Dors' robotic or human nature is of no concern to him: he loves Dors for Dors, even after being confronted definitively with her robotic nature. Dors' intelligence and knowledge of history become quite important to the Theory of Psychohistory.
In 12,020 GE Seldon gave a talk about his fledgling theory of psychohistory at the Decennial Convention, which caused Cleon I to express interest in him. At the urging of Chetter Hummin (a.k.a. R. Daneel Olivaw), Seldon first moves to Streeling University to continue his research without his interference. That is where he is introduced to Venabili, a history professor, and she is assigned the job of guarding him. She sticks with him as he moves to Mycogen, and later to Dahl and to Wye. Hari Seldon, meanwhile, guesses that Dors must be one of the ancient robots of Mycogene legends by the end of their journey. Despite of this, it is at the this point where Seldon and Venabili decide to marry and adopt Raych Seldon as their son. While at Dahl, Venabili has an opportunity to show her incredible skills at fighting. After saving Hari Seldon's life during an assassination attempt on the first year of his First Ministership, she receives the nickname "Tiger Woman."
When Raych Seldon marries Manella, Dors immediately shows her dislike for her and does not change that opinion until her death.
Prior to Hari Seldon's sixtieth birthday party, Dors begins suspecting a plot to end Seldon's life. The only basis for her assumption is a "dream" young Wanda Seldon had while in Hari Seldon's office. The dream turns out to be an actual conversation between two people, one of them talking about "lemonade death." This is a reference to Tamwile Elar, a young and promising mathematician who is secretly working with the junta that has been ruling Trantor since the death of Emperor Cleon I. When Dors confronts Elar, the latter activates a highly-tuned electromagnetic machine used to inscribe equations on the Prime Radiant. While the magnetic waves do no damage to humans, Dors, being a robot, is affected by them. She kills Elar, who unfortunately is able to turn the magnetic machine on full power. Dors stumbles to Hari Seldon's office, explains what has happened, then dies in his arms.