What are the motifs in The Berlin Stories: The Last of Mr. Norris, Goodbye to Berlin by Christopher Isherwood?

The boundary between reality and fiction becomes blurred in several obvious ways in these stories. To begin with, both "The Last of Mr. Norris" and "Goodbye to Berlin" include several reality-based details of the city of Berlin (street names, etc.), as well as perhaps less detailed but equally specific historical background (such as incidents along the way of the Nazis' rise to power). While many fictional works do this same kind of real-life contextualizing, the author of these stories goes one step further.