It is clear that the relationship between the father and son in this short story has been marred by the father's greed and obsession with money for a very long time. The son feels he needs to visit his father and sympathise with him rather than doing it willingly, but when his father openly begins to reflect on his life and the mistakes he has made, the response of the son shows that a restoration of their relationship seems possible, as the following quote suggests:
The old man turned his head way. He actually wiped a tear from his eye. A glow of sympathy transported the younger man. He felt as though a sun had risen.
The use of the image of the rising sun in this quote, and the description of the son being "transported" by the sight of his father shedding a tear shows that his father had never showed such emotions openly before, and that the son feels that there is hope for them now that he is able to do so. However, the son's final offer of some money to his father causes the father to revert to his original rapacious self, with his face of greed and avarice, his "little face," dominating his expressions. The relationship between the father and son therefore is presented as being irrevocably ruined by the father's greed. This is the barrier that prevents true love being expressed, the "fly in the ointment."