We have not yet found out who the insurance companies say is at fault; however, I was rear-ended so it's pretty cut and dry.
The police came but refused to do a report because there were no injuries.
I have no policy at all for any car.
Question for your response: Why is it that I'd be held responsible for HIS deductible?
Thank you for the additional information. Your liability would be based on your fault only - not simply because you were driving, so if you were rear-ended and you did not cut anyone off or do anything that might have contributed to the collision I can't see how you would be liable for any part of the damages, including the deductible.
The insurance company that covered the passenger/owner also will cover you as a permissive driver if anyone in the other vehicle brings a claim against you, so ultimately it will be in your best interest to cooperate with them. It may pay for you to get a consult with a lawyer before doing so.
I was cooperating fully until he (the owner/passenger) wanted me to make false injury claims with the help of his attorney. So I stoped following the advice of his attorney; both are trying to make quick money. Would that be a good reason not to cooperate?
This may provide even more reason for you to speak to an attorney working solely for you. If you cannot afford one, keep in mind that one way or another you can be required to provide information about the accident, under subpoena if necessary. You can do that without assisting a fraud by simply telling the truth.