At the beginning of the story, Christopher have to go to the police station because he is accused to have killed the Mrs Shears's dog. His father come to pick him up and show his love by touching Christopher's finger instead of hugging him.
Next, in the chapter 79, his father get mad at Christopher because he has been asking about Wellington's death. So, Christopher promess that he will stop.
But Christopher talked to Mrs Alexander to know more about Mrs Shears. His father get even more mad at him and hit Christopher. They have a fight.
I ask you one thing Christopher. One thing!
By trying fiding the notebook his father took away from him, Christopher find out about his mother being alive with the letters. So his father explain everything about his mother and Wellington. He apologize
I killed Wellington
When Christopher go finding his mother in London, his father get really worried and look for Chrisopher everywhere. That show how much he really care about Christopher.
At the end Christopher's father offers him a dog and apologize again about everything. Christopher forgives him and their relationship improve.
Christopher. I would never, ever do anything to hurt you