First, Nick and his father do have a positive relationship in the sense that Nick's dad obviously wants to spend time with his son and wants to teach him about life and helping others. One gets the impression from the beginning of the story that Nick is used to traveling with his father, because he goes with his father to the shore and gets in the rowboat before even asking where they are going.
Likewise, Hemingway gives the impression that Nick's dad wants Nick to admire him and be interested in what he does. He comments at the beginning of his visit to the laboring Indian woman and specifically addresses Nick, trying to make him a part of the situation. When he and George discover that the new father has killed himself, Nick's dad's concern is for his son, and he asks that Nick be taken out of the hut. He eventually says to Nick,
"I'm terribly sorry I brought you along; Nickie," . . . all his post-operative exhilaration gone. "It was an awful mess to put you through."
Despite these positive qualities in the father-son relationship, there is also a sort of distance between Nick and his father. Nick's father seems to be forcing his own interests on Nick. When Nick finds out where he and his father are going at the beginning, he gives the lackluster reply of "Oh." When Nick's dad asks him how he likes being an intern, Nick demonstrates the same lack of enthusiasm and replies, "All right." Nick's father does not even seem to realize that his son finds the ordeal gruesome and longs to escape. This "distance," however, between the two characters could simply be Hemingway's manner of illustrating the strain that often occurs in parent-child relationships when the the child enters into young adulthood. Parents often try to force their interests upon their children and do not even realize that their children would like to pursue their own course in life.
Overall, the reader should infer from "Indian Camp" that Nick and his father share a typical relationship. Nick's dad is very honest with him and does not sugarcoat the trials of life, perhaps because of what he has seen living in a difficult environment and through working in the medical field. Nonetheless, Nick's dad seems to want his son to be prepared for life but still longs to shelter him from some of life's problems.