In what ways does Dana explode the slave stereotypes of the "house nigger"? In what ways does she transcend them?
Dana brings her modern mentality with her as she travels back in time. She is free, and she refuses to let anyone take that from her.
By speaking to Rufus as an equal, she explodes the slave stereotypes. When he uses a derogatory term, this is her response: “I don’t like that word, remember? Try calling me black or Negro or even colored.” Over time, she even tries to teach him to be a better person, to treat others better, and to see the world in terms of equality rather than in the barbaric terms his father has set up; in so doing, Dana transcends slave stereotypes. She knows she is not only Rufus's equal; with her views on equality, she actually transcends his small-minded ways. She will not lose her freedom, she will not back down, and she will not accept the world as it is.
Of course, slaves she meets also desire freedom and also stand up to tyranny. They have no escape from the time period, though, as Dana eventually does when she is dragged back through time to the 1900s.
Dana is not only educated—which Weylin tries to prevent slaves from being—but she is highly educated, a writer. Her very language and understanding of the world transcends any stereotype. She eventually ends up becoming Rufus's tutor, which explodes racial and gender stereotypes; a black woman is teaching a white man.
With all the power of her voice, Dana also wields silence with strength. After an encounter with Margaret Weylin, Dana muses about her distrust of Dana: "Maybe I was a little too silent." The fact that Margaret Weylin cannot totally control Dana or even completely figure her out gives Dana power and helps her transcend stereotypes.
By coming back in time multiple times, Dana throws uncertainty into Weylin's world, a world he has fought to control. At one point, he asks,"What are you?" He knows she transcends him in some way, although he fights not to know it and to shove her into boxes of his own construction.
The horrors of slavery change Dana—internally and physically. Still, she transcends them by changing the people she meets in various ways and by surviving.
The most obvious way in which Dana transcends slave stereotypes, or indeed, expectations for all humans anywhere, is that she can and does travel through time. This gives her extensive knowledge of what will happen, making her a kind of augmented wise woman.
The other ways she transcends/explodes stereotypes are much more mundane these days. She speaks directly to whites as equals, she expects fair treatment, she retains the capacity for compassion, she carries a broad perspective with her, and she feels desire openly, with little concern for power dynamics.