In the first chapter of Walden, despite its title "Economy," Henry David Thoreau writes, as does Carson McCullers, of the unpleasantness of life, the lack of hope in so many lives: The mass of men lead lives of quiet desperation.
This desolation, this lack of hope, this "desperation" is what McCuller's characters feel in The Heart is a Lonely Hunter. It is, in fact, what makes them grotesque, in the sense of Southern Gothic grotesques. For instance, after his wife dies, Biff Brannon, who owns the diner, lives alone now, having rearranged the bedroom so that he no longer is reminded of her because theirs was a loveless marriage. Although freed from her, Brannon yet lives a life that is isolated: He sits alone in the bedroom, thumbing through his twenty-year collection of newspapers, and, oddly, wears his mother's gold ring with his wife's perfume sprayed on himself, and washes only his upper body, ignoring his manly parts in his new passivity.
But, he does have some interaction with customers such as Jake Blunt, with whom he talks and lends money. Later, he is one of the several who visit the mute Stringer in his room in the boarding house. Somewhat puzzled, he observes when Mick and Jake talk to the deaf Singer. After Singer's death, a desolate Biff Brannon wonders if, perhaps, love may be the only solution to loneliness and human isolation, man's desperation.
Perhaps then, you can make Thoreau's statement about "lives of quiet desperation" as thematic to a study of the grotesques (people who are deformed physically, spiritually, or mentally) of the Southern gothic novel, The Heart is a Lonely Hunter. For each character has his/her odd and strange qualities, and he/she searches for a solution to alienation and isolation. Flannery O'Connor, a Southern Gothic writer remarked,
In any case, it is when the freak can be sensed as a figure for our essential displacement that he attains some depth in literature.
Carson McCullers's "freaks" do attain depth.