Her glance moved beyond the white man's face to the passengers seated behind him. Four or five black faces were watching, two belonging to soldiers still in their s***-colored uniforms and peaked caps. She saw their closed faces, their locked eyes, and turned for compassion to the gray eyes of the conductor. (1920.19)
Helene's encounter on the train suggests that race doesn't instantly create a sense of community or shared experience. The Black soldiers are unwilling or unable to help her out of the situation with the conductor. (Mind you, they may need to be careful, too.) This reminds us to resist the urge to lump all people of one race together without accounting for differences and distinctions.
When he first came to Medallion, the people called him Pretty Johnnie, but Eva looked at his milky skin and cornsilk hair and out of a mixture of fun and meanness called him Tar Baby. (1921.32)
Tar Baby's "whiteness" comes up at several points in the novel. For the people in the Bottom, he is the minority, not them. Note the irony of Eva's naming him "Tar Baby."
He would have left him there but noticed that it was a child, not an old black man, as it first appeared . . . (1922.86)
There is a complete disregard for humanity in the bargeman's racism. Had Chicken not been a child he would have been left in the river to rot, his family never knowing where he was or what happened to him.
Jude and Nel were laughing, he saying, "Well, if that's the only way they got to show it – cut off my balls and throw me in jail – I'd just as soon they left me alone." (1937.177)
Jude is responding to Sula's declaration that Black men are the "envy of the world" (1937.176). In doing so he articulates the very stereotypes that she offers as evidence of this envy: that Black men's sexual appetites need to be controlled. Jude can laugh about it because he's with Sula and Nel, but the fact is that all three of them know there are prejudices Jude must face.
In that way, they regarded integration with the precisely the same venom that white people did. (1939.3)
The men in the Bottom accuse Sula of sleeping with white men, and this very possibility elicits fury. The only way the townspeople can tolerate the idea of a white man and a Black woman sleeping together is if the woman is raped. The Black residents of the Bottom have no wish to interact with white people.
Ajax didn't seem too bothered by any of it. More annoyed and inconvenienced than anything else. He had had several messes with the police, mostly in gambling raids, and regarded them as the natural hazards of N**** life. (1939.107)
Ajax's experiences invoke the idea of institutional racism. Policemen are part of a larger institution, and their individual racism is part of a larger system of prejudice and discrimination.