In the most literal way, the purpose of Eldon and Franklin's walk is to take Eldon to the ridge where he will be buried. A heavy drinker for many years, Eldon is dying of liver failure and realizes that his days are quite numbered when he summons his son to visit him. After initially hesitating at this request, Franklin agrees to take Eldon on a forty-mile walk so that his father can be buried as a warrior, which is his father's dying wish.
Eldon has another purpose for asking his son to take this walk with him. He has been largely absent from his son's life, abandoning him when Franklin was just a few days old and only periodically showing up in his life. Typically, these visits have ended disastrously because of Eldon's addiction to alcohol. Franklin therefore does not know anything about the struggles and losses that have led to Eldon's alcohol dependency. In fact, Eldon has never even shared any information about Franklin's mother with his son. Through this walk, the father and son are afforded the needed time for Eldon to share his own painful history with his son for the first time.
At first, Franklin's purpose is simply to comply with Eldon's wishes because the man is his father and is dying. Yet as they journey together, Eldon begins to open himself up to hearing his father's stories and understanding why Eldon is such a broken man. Bunky, who has served as Franklin's guardian, has refrained from sharing information about Franklin's mother with him, telling the boy that this is Eldon's story to share. Franklin desperately hopes that this walk will reveal some information about her. Although Eldon's remembrances of Angie leave Franklin devastated, he finally has some understanding of his heritage after hearing his father's stories about her.