Under the circumstances, Linda's not in a position to refuse Mr. Sands. As a slave, she has no rights and therefore has no choice but to let herself be sexually exploited by a white slave master. If she doesn't give herself to Sands, there's every reason to believe that he will take her by force. That was the appalling reality that many slave women faced at the time.

One could also argue that Linda gives herself to Sands as, initially, he presents himself as her protector. At first, Sands comes across as the antithesis of the wicked Dr. Flint, and Linda's only too pleased to find someone whom she thinks will protect her and her children.

Yet it soon becomes clear that Sands is just as much of an exploiter as Flint, and he takes advantage of the situation to have his wicked way with Linda, as so many other men in his position used to do on a regular basis. In offering protection to Linda, he's effectively grooming her for the purposes of sexual exploitation. But even if Linda had known about this from the start, there was very little she could've done about it. As a slave, she would not have been able to resist.