Final answer:
Dana's existence after killing Rufus in 'Kindred' is explained by the time travel element in the narrative, which allows her to return to her present despite the paradox.
Step-by-step explanation:
In Octavia Butler's Kindred, the narrative element that explains Dana's continued existence despite killing Rufus is time travel. Dana, the protagonist, finds herself repeatedly pulled back in time to the antebellum South where she meets Rufus, an ancestor whose life she must save to ensure her future existence.
However, when she eventually takes Rufus's life, the time travel mechanics of the story allow her to return to her present, 20th-century life, as the paradox of her intervening in the past had already woven her actions into the fabric of her existence.