Imagine a kind, loving, patient parent slapping a child for not making a goal. Or a mean, obnoxious parent offering to buy pizza for the team after a terrible defeat.
A strong man bending down to rescue a kitten stuck in a drain. A lightweight lifting a minivan off of a trapped little boy.
A dictator changing stripes and setting up a democracy. An elected leader suspending government to become a dictator for life.
Your task is to write a story in which the protagonist does something totally unexpected based upon what the reader knows or intuits about that person. The wider the discrepancy, the better.
Have fun with this one.