Medicine River is a complex novel full of equally complex themes. One of those themes is the importance of identity and heritage. Will Sampson, the protagonist of the book, has several questions about his identity, the main one being who his father is. He knows and lives with his mother, Rose, a Native American Blackfoot woman, but he has yet to meet his elusive father, a white man who abandoned his family years ago. The only connection Will has to his father are letters that his mother saved from Will's father written to her. Unfortunately, Will's mother catches him reading the letters and beats him severely, so Will cannot finish reading them, and thus, he doesn't learn the truth about his father and the hole about his identity is never closed, leaving him with unresolved emotional issues.
Another prominent theme in the novel and one especially prominent in chapter 13 is the idea that stereotypes, particularly those about Native Americans, are not always true. For example, Will and his best friend Harlen are Native Americans, but like pizza, football, and play basketball, just like most Americans or Canadians. Similarly, Will is a photographer, despite the fact that some Native Americans believe photographs steal souls. In this chapter, Susan, a white women whom Will is dating, is surprised to learn that will is a photographer. Her preconceived notions of Native Americans prohibited her from entertaining that idea before meeting will, and this meeting, ultimately, opens her eyes.
Finally, an equally important theme is the fact that strong women can also have imperfections. The reader knows that Rose, Will's mother is a strong Blackfoot woman who raises her children on her own with no help from their father, but she also seems to be weak when the subject of their father is brought up. Bertha Morley is equally as strong as Rose in that she has been in abusive relationships in the past, but still has hope and takes care of herself. In chapter 13, she chooses to join a dating service which she humorously calls an "escort service." Although she is initially presented to the reader as a direct woman, she doesn't seem to have very high standards. For example, on her application she writes:
Whites are okay. Should have his own job and not be married. I’d like someone tall so I can wear heels when we go out, but short is okay, too (178).