Detta Would Hate a Black Roland Just as Much as a White Roland
I keep responding to threads, and keep having to restate the same point about Detta.
Her bigotry does not define her. Her general hate is the more important aspect of her character. If Roland was black she wouldn't suddenly start liking him. She is a ball of hate, indiscriminate of race.
Her arc is not defined by Roland and Detta overcoming their differences. She never overcomes these differences; she is consolidated into the character of Susannah who has the strongest aspects of both Detta and Odetta. Detta doesn't have a character arc. The person who is all three (Susannah, Detta, and Odetta) has the arc.
Roland's white-ness has little bearing on how Detta perceives the world. It is simply how she chooses to attack Roland and her new surroundings on the beach of the Western Sea.
If Roland was black she would find something else to hate about him.