A river runs through it

I have been thinking about this book some and wondering about Norman Maclean's brother in law. In the book he is pretty much portrayed as insufferable and Norman seems to really dislike him at times for good reason. Norman's wife and mother in law care for him and try to do what is best for him as best they are able. Meanwhile Norman's own brother is portrayed as an honorable man who struggles with fighting and maybe alcohol and gambling.

My first few times reading the book I pretty much took it at face value. I have started to wonder if maybe the brother in law is not just meant as a contrast to paul but rather I parallel. I have started to wonder if Norman just has a big soft spot for his own brother Paul and his wife is much the same with her brother. Norman seems to desperately care for Paul in a way he does not for his brother in law but I cannot help but wonder if this is just due to growing up together. Maybe if Paul was his brother in law he would just view him as an aggressive drunk in over his head with the wrong people? And if his wife's brother was his real brother he would have a big soft spot for him the way she does? I don't think Norman intended it that way but it is interesting.