The Rambam (Hilkhot Ta’aniyot 1:4) writes that fast days are designated as times for repentance. In the first chapter, he discusses fasts decreed in a time of distress, during which one should cry out to God.
The crisis in the book of Esther begins as a result of Mordekhai's refusal to bow down to Haman. What was the reason for this refusal, and why was Mordekhai willing to jeopardize the safety of the Jewish People as a result?