Monsters don't cry. The only time they do is when they fail. Right?
When Princess Celestia sent Twilight and her friends to apprehend a murderous, thieving draconequus, they thought it was clear cut. A heathen, brute, menace to society. Whatever they chose to call it, it was evil. So what happens when Twilight is separated from her friends by the monster?

Some creatures can't cry because they are mentally ill, or take pleasure in it. Others can't cry because they have no tears left to shed.

Set shortly after season 4, right before season five.