20 years ago on a small fleet in big company we had two checkers of opposite personality.
One a true gentleman and tutor. The other a vindictive troll.
The nasty one felt he had been hard done-by by the company and duly took it out on his checkee's.
After a check ride with first fellow, l asked why he was so pleasant, thorough and assisted with any 'grey' areas with fairness, the complete opposite of his colleague.
His response was straight forward enough..."One day you may be my check-captain!"
halas