The two main characters in "After Twenty Years" are Jimmy Wells and Bob. The author probably gives the reader Jimmy's last name to make his character more of an identifiable aspect to his character. Bob's last name is not given, which lends a bit more mystery to this mysterious character.
Jimmy (as the story unfolds) has gone on to a career as a police officer. This fact is purposely withheld from the reader. Both men had been friends many years earlier. At that time, they had determined to meet up twenty years later to see how their lives had turned out. When we discover the answer to this question, we can ascertain that the the character of Bob might be described as "round," in that he had changed "After Twenty Years." Jimmy's character, meanwhile, might be described as "static," as he remained essentially the same as Bob had known him so many years ago.
jimmy wells ,bob n a man