James's character

He is obviously one of the two most complex characters in the film(along with Gary-Berenger).I mean,he actually represents the daily part of Theresa's life in work,family and society but Brooks does not hesitate to stain his clean cut image with facts like his obsession with a person,his attitude of twisting reality by telling dirty stories about his family and deny them after a second and even, a person with outbursts not far from the type of street punks like Tony which Teresa hung around with(remember this blood and gut scene just before Theresa's last scene with her father.In the previous scene,James looks horrible and almost unbalanced while immediately after,Mr.Dunn shouts at his daughter for hurting this wonderful person.
Maybe someone who has read Rossner's book could tell about the meaning of the scene where he narrates that horrible story about his parents and laughs about it afterwards.He got Theresa spooked like ''wow,another weird character i my hands'' and then she came back to night life.I haven't been able to read the book yet,but I know that Brooks took essential liberties in his adaptation of it.
Anyway,he is a very puzzling character and a proof that this film after 40 years still gives food for thought.