I had a best friend who was an attorney. They taught them in law school that if you ask a suspect "what did they say you did?" instead of "what did you do?" you will get the truth.

Ideally, I would like the answer to this question to be "I don't have any enemies". Viewing someone as an enemy is not a coincidence. If your are a healthy person you should not be at war with anyone.

If they start describing a sordid story of drama don't doubt that it is the truth, even though they end it with "they are insane". And even though you want to side with them.

Truth reveals itself early. Don't be afraid to ask.

Other variations of this questions is:

"what do you're biggest critics think your biggest weakness is"