However, we can speculate based on some clues:
* Writing: Obviously, writing is a major part of his life, and it's likely he enjoys the process of creating stories and characters.
* Reading: As a prolific author, he likely enjoys reading widely, especially within the genres he writes in.
* Family: Patterson has spoken about the importance of his family, and he may enjoy spending time with them in his free time.
* Travel: As a successful author, he probably travels a lot for book tours and other events.
* Sports: He's an avid fan of the New York Yankees and has even written a book about them.
Beyond this, it's hard to say what his hobbies are. He may have a passion for music, art, cooking, or any number of other things. We simply don't have access to that information.