German money was practically worthless after World War 1, so people in Berlin turned to prostitution to get their hands on Japanese and especially American money. People of both genders and from all layers of society did this, even high ranking military people all the way up to generals. This resulted in Berlin becoming a favorite place for foreigners to try out their own sexualities because you could get anything you wanted for 1 dollar, and no one had to know what you had been up to in Berlin.
Especially the Americans enjoyed getting military men to do all sorts of things, just for the hell of it, and that lead to these two characters who have been swimming around in my head for about two years now, yet don't have names. The American basically becomes the German general's sugar daddy.