What important feature does Jeannette notice about Dinitia, and what might this observation foreshadow?

I'm not sure what you mean here. Dinitia Hewitt is an African American classmate of Jeannette’s in Welch. Dinitia and her followers bully Jeannette at Welch Elementary. The two later become friends after Dinitia witnesses Jeannette helping a neighbor escape a dog attack. Dinitia becomes pregnant in seventh grade and is arrested for stabbing her mother's boyfriend to death. It is implied that her mother's boyfriend sexually assaulted Dinitia.