Soldier's Home by Ernest Hemingway is a typical Hemingway story in which a solitary hyper-masculine figure is misunderstood by the women in his life. The sense of masculine viewpoint and a sort of masculine solidarity that existed in Krebs' military life but not in his life after he returned home to a feminized environment is enhanced by the naming conventions used in the story.
In the military it is traditional to refer to men by a last name, preceded by a rank when demanded by formal etiquette. This was also true of schools at the time when this story was written. Within military and school environments, this form of address (unadorned last name) was typically used from superiors to inferiors. Since the first time military recruits or schoolboys heard each others' names, it was in this form, often old friends retained this form of address. It emphasizes the masculine camaraderie that is not understood by Krebs' mother or sister.
The sister uses "Hare" as a diminutive form of Harold to indicate affection for her older brother. This nickname, and the bonding over baseball, illustrate an the affection between the two, reminding Krebs of his lost innocence, although his sister too leads him into a form of inauthenticity in her discussion of being his "girl."