While both Flannery O'Connor's stories have the theme of “redemption through catastrophe,” Hulga and Mary Grace differ in certain ways, although they share many similarities.
- Mary is the agent of the redemption in "Revelation," while Hulga is the recipient of the redeeming revelation in "Good Country People."
- Hulga believes in nothing; Mary Grace studies Human Development.
- Mary Grace recognizes the evil in Mrs. Turpin,
"Go back to hell where you came from, you old wart hog," she whispered.
However, Hulga falls victim to Manley Pointer's evil.
- Mary Grace's name is certainly indicative of her role in Mrs. Turpin's receiving of the grace that can lead to her redemption after her dream that reveals her sinfulness. In a similar significance of name, Hulga's having changed hers from Joy indicates her acceptance of the ugly nothingness of life.
- Just as Mary Grace recognizes the evil in Mrs. Turpin, calling her "old wart hog," like Hulga she enjoys causing Mrs. Turpin pain.
- Both Mary Grace and Hulga are disfigured physically
- Both Mary Grace and Hulga are disgusted by the banal conversations of the people in the waiting room and Mrs. Freeman and her mother. They both refuse to engage in conversation with the objects of their scorn.
- Both girls hate hypocrisy. When Mrs. Turpin begins to feel sorry for Mary Grace, the girl looks at her "as if she had some special reason for disliking her." Likewise, Hulga slams the door to her room when her mother talks with Mrs. Freeman she scowls, showing her disapproval of them.
- Mary Grace is classified with "freaks and lunatics"; Hulga, too, is a "freak" as she has the artificial leg.
There is some lack of clarity in your question. There is no character named "Mary Grace" in "Good Country People," though Hulga, of course, is critical to the story. She is educated, angry, superior, self-sufficient and subject to living on the periphery of life, somewhat due to self-ostracism. Do you mean Mary Grace from O'Connor's other short story, "Revelation"? If so, perhaps you would repost your question with more clarity as to the particulars.