How does Harriet Beecher Stowe portray white southerners?
Stowe portrays white Southerners, specifically slaveholders, in a variety of ways. On the one hand, there was Mr. Shelby, Uncle Tom's first owner, who sold him due to debt. Mr Shelby is a decent man, but he sells Tom out of financial need. We see in his wife's reaction to the news (she is bitterly opposed to it) some evidence that even slaveholders could be aware of the immorality of the institution of slavery. Describing slavery as a "bitter, bitter, most accursed thing," she unsuccessfully tries to change her husband's mind. Similarly, St. Clare, who purchases Tom, is a decent man who would have granted freedom to Tom had he not been murdered, and Shelby's son is equally sympathetic to Tom and other enslaved people.
But the enduring image of the book, and one that outraged readers, was that of the evil Simon Legree. Legree is a profane, brutal, wicked man who, "blinded by furious, despotic will," beats Tom to death in one of the book's final chapters. For Stowe, Legree is meant to represent slavery incarnate, and his brutal murder of Tom, a near-saintly figure, demonstrates the evil nature of the institution. For Southerners, who by the 1850s were claiming that slavery was a "positive good," one in which benevolent masters treated their slaves with paternalistic kindness, Legree represented a mockery of the image they tried to portray. The overall portrayal of slavery as brutal and dehumanizing angered Southerners even as it gave a shot in the arm to the abolitionist movement in the North.