Lucy Walker (April 30, 1826 - October 5, 1910) moved with her parents and siblings to Nauvoo in the spring of 1841. She saw her family fall apart the following January when her mother died of malaria, Joseph Smith sent her devastated father, John, on a mission, and her and her nine siblings were split up upon Joseph's instruction. Lucy, along three of the other older children, were taken in by the Smiths. She was fifteen at the time.
"You have Just such a family [daughter?] as I could love." Joseph Smith, Jr.
One day Joseph decided to teach Lucy about plural marriage. He told her that God told him to marry her. He told her it would save her mother. He told her it had to be secret for now but he would recognize her openly as a wife one day beyond the Rocky Mountains. He told her to pray about it. When Lucy hesitated he told her she had until the next day to decide adding that it was a commandment from God. He told her that if she refused heaven's gates would be closed to her forever.
What would you have done? Lucy was distraught. She, of course, decided to place herself on the altar. They were married by William Clayton on May 1, 1843 - the day after her seventeenth birthday. Emma, who was away on business, was not privy in the slightest to this marriage. Neither was Lucy's father.
Lucy, speaking of her marriage to Joseph, stated that she lived with him as a wife (THEY HAD SEX) but it "was not a love matter [...] - at least on my part it was not, but simply the giving up of myself as a sacrifice."
Lucy married Heber Kimball after Joseph's death. They had nine children: Rachel, John, Willard, Lydia, Ann, Eliza (mother of Spencer Kimball), Washington, Joshua, and Franklin.