There are so many things to fear: spiders, heights, flying, eating out, strangers. Sometimes those fears are crippling. The subject can’t leave the house because of the possibility of encountering his/her worst fear.
Then there are those who fear nothing. It must be terrifying as a parent to watch your child climb high into a tree or scale a pole or ride a bike down a steep hill when you’d never do those things yourself.
Your task is to write a story in which your character has a hidden phobia, which is revealed in a dramatic fashion.
Have fun with this one.