back in time to a location that is near Rufus, and every single time Rufus is in grave danger: he is near drowning, he has broken his leg, or he is about to receive a beating that could end his life. Dana always swoops in and saves him in one way or another, so it appears to Rufus that Dana is his guardian angel. Dana will eventually explain to Rufus that she is travelling through time and gets pulled back to his time period whenever his life is in danger. Consequently, Rufus knows that Dana is somehow bound to help him, and this gives him a bit of leverage over Dana. Dana is also hurt by the fact that she is black, and chapter four shows readers how Rufus uses that fact against Dana. Rufus tells Dana that he needs her to help him with his goal to have sex with Alice. Rufus says that if Dana doesn't convince Alice to do this, then he will make the women's lives miserable. Dana agrees to help. She is disgusted with herself for helping, but Dana also believes that she will cease to exist if Alice does not begin birthing Rufus's children.

I understand what this question is asking, but I would definitely hesitate to say that Rufus and Alice have a relationship that Dana gets in the middle of. I would hesitate to say that for two reasons.

First, I wouldn't say that Dana finds herself caught in the middle of the relationship. Dana is very responsible for the relationship existing in the first place. There wouldn't have been a relationship without Dana encouraging Alice to stop fending off Rufus's advances. Second, I hesitate to call what Rufus and Alice have as a "relationship" in the traditional boy/girl/man/woman/love sense of the word. Alice is "with" Rufus to protect herself. She can go along with his advances and sexual demands, or she can be beaten and raped.

Dana's decision to convince Alice to have a "relationship" with and have sex with Rufus is entirely a selfish decision. Despite the fact that Dana lives in 1976 and has never see Back to the Future, she adheres to the movie's time travelling logic. Dana knows that her family line comes from Alice and Rufus. She believes that if Alice and Rufus do not produce children, Dana's family lines will cease to exist. Therefore, Dana would cease to exist. The logic makes sense as long as only one timeline exists and changes to the past can influence a future. This is why Dana uses both Rufus and Alice. Dana needs both of them to survive and produce children in order to ensure her own future existence.