In early versions of d&d fictional positioning was coined as the idea of where your party stood in morale compared to the enemies. Fictional positioning is basically the idea of leveraging fictional elements of the role-playing world in combat, for example, if you understand how to manipulate the emotions of your enemy you may be able to stop combat. If you can present to them a reason to stop then they should. You could also lower the morale by performing specific actions or taking out specific opponents.

Effectively fictional positioning is how role-playing affects combat systems in d&d and other fictional role-playing games