This is somewhat of a trick question because a hiring authority is trying to find our definition of what a difficult person might be. Whatever you do, don't vilify, criticize, or present that person in a bad light. Describe the difficulties that the person caused you and everyone else in the organization in objective ways, then describe how you dealt with the situation. Bit presents the person as a positive for you. He or she was difficult to work with/for, but I found a way and learned so much form him or her. In the end, it turned out to be a great learning experience, even thou painful at times.
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