How did the relationship between Eliezer and his father change in the course of a year on which the book focuses?
Eliezer changes tremendously throughout Night. He becomes less and less caring. He definitely becomes less and less spiritual. The Germans have reduced the Jews to less than human. Elie admits that he has to worry about his own survival. His father is sick and has become a burden. Elie feels guilty for feeling this way, but he has become hardened by the terrible conditions in the concentration camps.
Food is so scarce until Elie is a walking corpse himself. He is losing his faith in God. He cannot understand how God could allow him to go through the things he is going through.
Elie can barely survive as it is. Now that his father is sick just makes everything more complicated. Elie stands by when his father is beaten by an SS officer. He does nothing to try and stop him. He has become concerned with his own survival. He realizes that if he tries to intefere when his father is being beaten, he will suffer more so himself:
Eliezer's father asks an SS officer where the lavatories are and the man strikes him. Eliezer does nothing for fear of being struck himself, but he vows never to forgive the staking of his father.
When Elie's father dies, Elie sheds no tears. He has lost all feelings and emotions due to his horrific conditions. He only thinks of one thing after the death of his father and that is eating. He is so starved until he has lost human reasoning:
Eliezer has no more tears to weep, and in his weakened conscience he feels freedom.