Conversation so far:
What is a notable friendship Gary Cooper had?
Gary Cooper's twenty-year friendship with Ernest Hemingway began at Sun Valley in October 1940.
What was Gary Cooper and Ernest Hemingway's friendship like?
The two shared a passion for the outdoors, and for years they hunted duck and pheasant, and skied together in Sun Valley.

Question: What other qualities did their friendship have?
Self-contained rewrite: What other qualities did the friendship between Gary Cooper and Ernest Hemingway have?