What relationships experience great change in the novel To Kill a Mockingbird?

The most obvious answer to this question probably concerns
the relationship between Boo Radley and the Finch children. Both of the kids eventually
learn that the rumors spread about Boo could not have been true, since his gifts of
kindness left in the knothole--as well as Jem's mended pants and the blanket placed upon
Scout's shoulders--showed that he was far from the scary ghoul of neighborhood lore.
Scout actually gets to see Boo for herself in the end, and she proudly accompanies Boo
back to his house in the final chapter.

Other relationship
changes:

• Calpurnia
  and Scout.  Scout seems to despise Cal in the first
  chapter, but she comes to recognize that the housekeeper loves her. Scout even wants to
  visit Cal at her own
  house.


• Dill and
  Scout.  Dill begins as just another interesting playmate,
  but he and Scout soon become engaged; they even sneak kisses when Jem is not
  looking.


• Alexandra and
  Scout.  Neither Jem nor Scout particularly like their aunt,
  but by the end of the story, Alexandra has made some headway. She shows true, loving
  kindness following Bob Ewell's attack, repeatedly calling Scout
  "darling."


• Mrs.
  Dubose and Jem.  The much
  despised old lady never wins over Jem completely, but he is truly upset upon hearing of
  her death. Atticus' explanation of her drug addiction helps Jem to understand her
  better.


• Atticus and the
  Cunninghams.  The Cunninghams, leaders of the Old Sarum
  crowd, show up at the jail willing to kill Tom and harm Atticus if necessary. After the
  Finches make their stand, the lynch mob leaves out of respect for Atticus and his
  children. Later, Atticus identifies one of the Cunninghams as the holdout on the
  jury.


• Mayella and
  Tom Robinson.  One moment, Mayella is kissing Tom; a short
  time later, she accuses him of rape.