How does Wallace create back stories for the characters?

Wallace continues to introduce new characters throughout the novel, even up to Chapter 36, because it shows the back stories of some of the characters who will be significant later on. Some are already significant, but they have other future characters in their back stories. Wallace also creates in-depth patterns that exist between some of the characters that the reader does not expect. For example, Joelle dated Orin but also has connection to James, his father.