Examples:

• What if alana isn't just a passing fancy?
• I had a passing fancy. Only, it didn't pass, it stopped.
• A passing fancy, that's all.
• Okay, so we prove that henry was impetuous And alana was a passing fancy.
• Long had I thought your feelings for Arathorn no more than a passing fancy and that in time you would turn from them and look around you at last.