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.
What other qualities did the friendship between Gary Cooper and Ernest Hemingway have?
Both men admired the work of Rudyard Kipling.
Why did Gary Cooper and Ernest Hemingway like Rudyard Kipling?
Both men retained as adults Kipling's sense of boyish adventure.

Question: what did Hemmiway and Cooper have in common?
Self-contained rewrite: What did Ernest Hemingway and Gary Cooper have in common?