I'm not sure what you are asking with this question, but I will try to answer it. When Dana's life is in danger, she is sent back to the present time of 1976. When Rufus is in danger, Dana is then sent back to the past. She must protect Rufus since he is the future father of her first woman who is listed in her family records.

The first time Dana is called back by Rufus is when he almost drowns in the river. Dana saves him, but a gun is aimed at her head, so she's transported back to 1976. The next time she goes back, Dana is caught teaching black children to read, and she is beaten for it, which causes her to go back to the present. Another time, Rufus sold a slave he felt was too friendly with Dana, and Rufus punches her in the face when she protests. Dana feels cutting her wrists will be the only way to take her back to the present, and she's correct. The last time Dana is sent back, Rufus tries to rape her, and she stabs him. Rufus won't let go of her arm, however, and when she returns to 1976, her arm is crushed.