One of the key ways in which the author of this book presents and develops character is through the motif of fishing, which of course is something that Paul and his brother learn to do from an early age thanks to their father. In particular, the strict religious principles and beliefs of Maclean's father are demonstrated through his attempts to teach his children of the sense of wonder of nature and that God can be found in the order of the four-count rhythm that he uses when he goes fly fishing.
Perhaps most interesting, however, is the way in which fishing is used to demonstrate Paul's character. What is fascinating is the lack of correlation that exists between Paul's life when he is fishing and in his personal life. Even Paul's father, as much as he disapproves of Paul's personal life and the kind of decisions he makes, has to begrudgingly admit there is a beauty and elegance in the way that Paul fishes. However, as his habits of drinking, gambling and short-term relationships with women show, his personal life has many problems and issues. Paul only seems to find peace when he is fishing, as it is an ordered existence that he can control.
Therefore, you might like to analyse the motif of fishing as a key way in which characterisation occurs and is presented in this memorable novel.