Sessethantis zh'Cheen, known as "Thantis" by close friends and relatives, was a member of the Cheen clan of Andor who dwell in Cheen-Thitar Keep in the Andorian province of Thelasa-vei on the Southern Archipelago. Thantis is a member of an old clan, and her chri'ze, Thirishar ch'Thane recognises that once, long ago, Thantis would have been considered an Andorian First Princess. Thantis is also an artist, lecturing on Betazed before and during the Dominion War. Thantis is the Zhavey of Thirishar ch'Thane's zh'yi, Shathrissia zh'Cheen, known as Thriss to close friends and relatives. Thantis loved her zhei completely and was devastated by her death.
Thantis and Charivretha zh'Thane were old antagonists, each supporting rival governmental parties on Andor. While Vretha is a Federation councillor elected from the ruling Progressive Party, Thantis supports the Visionist Party and holds a gathering for Andorian Visionists at Cheen-Thitar Keep during the Spring Water Festival on Andor, even as Vretha's political career is foundering and Vretha's chei, Shar, is present in the Keep. (DS9 - Worlds of Star Trek: Deep Space Nine novel: Andor: Paradigm)