Joanna Burden's father and grandfather had both been fanatic on the subject of freeing and helping the Negroes. Her grandfather and her half brother had been murdered in the course of trying to help the Negro race. Joanna, herself, was brought up with the idea that the "curse of the black race is God's curse. But the curse of the white race is the black man who will be forever God's chosen own because He once cursed Him."
When Joanna was very little, her father took her to show where the graves of her grandfather and her half brother were hidden. At the graveside, he admonished her to remember that her kin were killed not by a white man but by a curse, and that she has inherited that curse and that none can escape it. When Joanna asked her father if she couldn't escape it, he told her "Least of all, you." Therefore, Joanna was born and brought up with the idea that she must dedicate herself to raising the Negro up to a higher level. Until the appearance of Joe Christmas, Joanna had spent her life helping with Negro colleges, advising young Negroes, and contributing to various development funds.
Joanna should, therefore, have been the person who could have accepted Joe Christmas for what he was — as part Negro and part white. But she fails him. Having remained a virgin for over forty years, Joanna's initial response to sex was that of a fanatic. She enjoyed the corruption, and she even prayed to God to allow her to remain corrupted for a few more years. She even seems to enjoy the corruption even more by exclaiming "Negro! Negro!" as he makes love to her. Thus Joanna seems to enjoy the fact that Joe is a Negro and seems to make a distinction between his two bloods.
When she reached an age where she could no longer enjoy being corrupted, she began to resort to her forefather's religious fanaticism. She began to demand that Joe change his way of life. She offers him jobs, wants him to go to school, and tries to get him to pray. When he refuses, she decides that she must kill him. She would have succeeded if the old pistol had not refused to fire.
Thus, Joanna Burden stands as an ironic contrast to old Doc Hines. Both in their own way were fanatics over the subject of race. And both tried to kill Joe Christmas. But in terms of Joe Christmas, Joanna's attempt to destroy him was more dangerous because she tried to destroy his individuality.