Dors Venabili 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 as their son. Seldon considers Venabili to be human, although given her speed, strength, and intelligence, he suspects that she is a robot. In Prelude to Foundation, he maintains that Dors' robotic or human nature is of no concern to him: he loves Dors for Dors. He finds out that she was a robot for sure in Forward the Foundation. Dors' intelligence and knowledge of history becomes quite important to the Theory of Psychohistory.
The reader first encounters Dors Venabili in Prelude to Foundation. Chetter Hummin, aiding Hari Seldon and setting him off on The Flight. In 12,020 GE Seldon gave his speech 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 interferece. That is where he is introduced to Venabili, 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. Despite of this, it is at the this point where Seldon and Venabili marry, and adopt Raych Seldon as their son. While at Dahl, Venabili has an opportunity to show her incredible skills at fighting, and after saving Hari Seldon's life during an assasination attempt on the first year of his First Ministership, she receives the nickname "Tiger Woman."
When Raych Seldon marries Marcella, Dors immediately shows her dislike for her and does not change that opinion.