Dayuma (ca. 1931-2014) fled her people's tribal violence when she was only about 13 years old. Eleven years later, when Rachel Saint met her in February 1955, she was living in virtual slavery on a hacienda on the edge of the rainforest. She was the only Wao speaker Saint could find to help her with language study. It later became clear that Dayuma spoke a corrupted form of the language, having repressed or forgotten much of her native tongue. Nonetheless, Rachel Saint became convinced that God had chosen Dayuma to take the Gospel to her people.

In 1957, two Waorani women, Mintaka and Mankamo, left their people and made contact with Dayuma. They were members of her kinship group, people known as the Geketaidi, after Geketa (whose name is also spelled as Gikita), who was Dayuma's uncle and the oldest male. Before Saint and Elliot ventured into Wao territory in 1958, Dayuma returned a few weeks earlier to prepare the way for the outsiders' arrival. She explained that the Waorani had nothing to fear from the the two women (and later offered similar assurances regarding the Waorani to Saint and Elliot). She also arrived with gifts—trade goods the Waorani wanted—and strange stories about a creator God named Waengongi, after a mythical Wao figure. Because of her Wao identity, as well as her understanding of the outside world, Dayuma became an essential cultural bridge between the missionaries and her people. As time went by, she also became a major power broker in her community.

Rachel Saint taught Bible stories to Dayuma, who in turn, taught them to other Waorani. Saint was adopted into Dayuma's family group, and she and Dayuma became kin sisters. Both were strong willed and their arguments were legendary, despite a deep-seated loyalty to each other. Dayuma was the first evangelist to the Waorani, and some members of her extended family group continue to be among the strongest Wao Christians.