Because I was the manager, he was my supervisor for the 3 year term he filled. There was always a new chair, every 3 years. I could hold on. I didn't want to give him the satisfaction of chasing me away. Perhaps I should have left, but I didn't. Call me foolish, but I like to win.
He had to give me a final performance evaluation about a month before his term ended. It lasted, on and off, for a day and a half. I'm not kidding. Hours and hours of him asking me questions he could then use my answers against me. It was quite odd.
I reminded him a performance evaluation is a time for a supervisor to review the employee's work performance, and give constructive feedback to help the employee improve. Instead, we danced around his hatred for me. Just him and me. On and off for 2 days he asked me questions, and I tried to answer them very carefully.
Finally, he asked what I thought about working for him. I replied "Working for you is like running a marathon in 90 degree heat, with the flu." He was a runner, so I knew he'd understand. That ended the "review." A month later his term was up, and I had a new department chair who was quite wonderful. I won, sort of.