Write out Hemingway,The Sun Also Rises,characters. Looking at the last couple ideas in your list, you might realize that you're trying to find reasons for the negative traits that you first listed for the characters. Now the question is how do you frame these thoughts into a working thesis or working research question. Hemingway's story seems to deal heavily with man's struggle within himself and with those around him. This question allows a researcher to center attention on the personal values of the characters and how they respond to circumstances in the story.
Emphasis is placed upon decisions which have their origin in a code of behavior.
Step 2 - Use Search Engines To give yourself a broad view of all information that is available, you'll want to start by using the Internet search engines. The search generates 299 matches. The first couple of documents deal with literary chatrooms and discussion groups, which may reveal some information, but normally it is not extensive nor substantial. Keep scrolling down, looking for titles that pertain to your topic. 17 looks interesting.