> What to do with him regarding this behavior?

Based on the information you have provided, I believe you are in a classic **no win** situation.  Going to HR would most likely *not offer any relief*.

You have **three** options in my view:

 1. Tell **your employer** to find a new home for you.
 2. Just put your head down and do the work, **ignoring** the behavior.
 3. Find another place to work **yourself**.

Good luck with this situation.