What are the similarities and difference between Alice and Dana in Kindred?

In 's
historical time-travel novel , the , Dana, is repeatedly summoned back in
time to ensure the continuation of her bloodline. This rests on Rufus Weylin, a white
slave-owner, impregnating Alice Greenwood, who was born free, was a friend of Rufus as a child,
and was later bought by him to be his slave.

Here are some
similarities between Alice and Dana:

• 
  Both women are physically similar: "tall and slender and dark," and they
  resemble each other as family would, even though they are far removed from each
  other. This similarity in appearance (and in personalityboth women are
  strong-willed and stubborn) leads Rufus to consider them to be two halves of the same woman.
  Alice explains to Dana, "He likes me in bed, and you out of bed, and you and I look alike
  if you can believe what people say" (229). Rufus is physically (and perhaps romantically)
  attracted to Alice, while he relies on Dana to take care of him and to stimulate and support him
  intellectually.
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