1. 出乎意料的变化;难以预测的转变
Vagaries are unexpected and unpredictable changes in a situation or in someone's behaviour which you have no control over.

1. an unexpected and inexplicable change in something (in a situation or a person's behavior, etc.)

e.g. the vagaries of the weather
his wealth fluctuates with the vagaries of the stock market
he has dealt with human vagaries for many years