I felt sorry for this happening to someone once. I started a job and he theoretically was in charge of training me, but it quickly became apparent that I was better at the job than he was and that he wasn't very respected. Shortly thereafter he quit (ironically, perhaps, to fill the absence I had left at my previous job).

A few months later he had an assignment that brought him back to my then-new job's premises. He tried to arrange lunch with us but no one was interested.