In the starting parts of the book they have a traditional father-son connection but as we go further in the reading of the novel we see in chapter four that the father is beaten and that should have called for a compassionate response Elie but instead he is overpowered by the feeling of anger and as Eliezer is the stronger one now, they do not have anyone else, just each other.
At the end another change is noted when Eliezer’s father passed away, he is feeling a sense of relief which in later part of his life he regrets.