Ma Joad goes about her days selflessly, cooking, cleaning, and nurturing her family. She doesn't talk about her wants or needs, except to dream about having a little house one day next to an orange orchard – a dream which she quickly realizes will never be. Rose of Sharon is all about herself. She talks her mother's ear off about the kind of luxuries she'll bask in while in California. And when these luxuries don't immediately flock to her, she grows grumpy and dejected. Ma Joad's great joy in life is her family, while Rose of Sharon is all about her own wants and needs. We can't help but contrast these two dames, because they are related, and because they are the only two grown women that we really get to follow in The Grapes of Wrath.
Both loners, both single men, both carry the weight of guilt the size of a giant blue whale on their shoulders. Upon close inspection, Uncle John and Reverend Casy have oodles in common with each other. John's guilt stems from failing to get his wife a doctor when she complained of a stomachache (which turned into a fatal appendicitis), and Casy's guilt stems from his days as a preacher when he did not do as he preached (i.e., he slept with lots of women). However, they cope with this guilt in very different ways. John is compelled to confess his sins, perform random acts of kindness for his family, and drink himself silly in order to chase away a feeling of guilt. Reverend Casy wants to be among the people, wants to help migrant workers cope with the dismal circumstances of California. He finds his solace in fighting injustice. Where John turns inward, Casy seems to look outward at the world around him.