Historian Amy Tanner Thiriot summarizes how Green Flake became enslaved to Brigham Young.
Amy Tanner Thiriot, Slavery in Zion: A Documentary and Genealogical History of Black Lives and Black Servitude in Utah Territory, 1847–1862 (Salt Lake City, UT: University of Utah Press, 2022), 113-114
In summary, Agnes Flake seems to have hired out Green Flake to Brigham Young for a year to help solve a problem involving the separation of enslaved families and the control of Flake's labor. Brigham Young then freed Green Flake. William J. Flake reported more than forty years later that his mother donated Flake as tithing, but no known record confirms that Agnes understood tithing to be involved in the transaction, and the laws and customs of Southern slaver, the provisions of An Act in Relation to Service, the memories shared by Green Flake's family, and Amaasa Lyman's letter contradict William Flake's childhood memory. Although Green Flake left no record of his understanding of the entire incident, his relationship with Brigham Young continued to be an important part of his family's heritage. Many years after both men died, a granddaughter recalled, "Green shed tears at the death of Brigham Young and helped dig his grave and was at the funeral of the beloved President."