How does dionysius mocking damon for taking pythias’s place advance the plot of the story?

Dionysius’s desire for total control and power affect the story’s plot in “Damon and Pythias” when Dionysius character was hot - tempered and imperious and anyone who angered him was put to death. In this situation, people in Syracuse were afraid to make a statement about him because they will be put to death. And so when a day came that he was informed that a young man named Pythias had been heard complaining against the cruelty of Dionysius, he condemned the youth to die.

theres no poem plesae include that

what does the teacher mean