Theme: Hemingway's theme or subject for "Cat in the Rain" is one that appears in many of his stories and novels: the disillusionment of young Americans (specifically in this story--the disillusionment of American brides with love the happily-ever-after endings).

In regards to characterization, most of Kitty's and George's characteristics are demonstrated not by what they say but more so through their thoughts and actions.  For example, Kitty is unhappy with the tediousness of her marriage and the lack of attention George pays her.  The reader knows this through Kitty's thoughts about the kind and attentive manner that the hotel keeper shows her. Granted, she does start to rant about all the things that she wants, but the reader must put all of those rather empty words together to know that Kitty internally does not want things--she wants attention.

Similarly, George's actions betray his disinterest in and nonchalance about his marriage and Kitty's feelings.  He is reclined on the bed and half-heartedly offers to get the cat for Kitty, but does not get up.  He is the same position when his wife returns to the room. He dismisses her words and feelings by continue to read throughout their conversation.

Thus, Hemingway's masterful use of stream-of-consciousness technique and characterization through action and gesture advances his theme in "Cat in the Rain."

For a very helpful understanding of this story, click on the awaytoteach link below to view a short but powerful presentation of the story. After the site, comes up, scroll down to "Jenni Lee's Cat in the Rain."