used to describe a situation in which people do not follow the usual rules of behavior and do things that are normally considered unfair Sure, it was underhanded to steal his customers, but all's fair in love and war.
In two different settings, there may be different trials to be faced or different rules. Depending on where the character is will affect the way they act. For example, if a character was at a fancy restaurant they may act differently than they might've if they were at a crime scene. I hope this is helpful!!
:)