In the beginning, Greg dreaded getting a lecture from his father. In the end, he looked forward to the lecture because he knew what to expect.
The narrative implies that Greg was upset and unwilling to listen to his father's admonition.
In the end, we can assume that this changed because Greg was awaiting his father's lecture.
The change was due to his father wanting to tell him about losing his son.
I know this probably isn’t 150 words, but it’s a start.
