You know, there is a great mystery surrounding the song "My Friend Jim," a mystery of Shakespearean proportions: after limning all the faults of Jim throughout the song--all his quirks and oddities, his foibles, his angularities--why does the narrator still refer to him as "my friend"? I think this is the real intriguing focal point to the whole song. Upon these sorts of things great literature is written (or at least used to be).
In other words, although the song is ostensibly about Jim, the fact that he's still "my friend" paints an even more intriguing portrait of the narrator.