Anyone that has played in one of my games can attest to the fact that I consistently use non-player characters(NPCs) in my campaigns. NPCs can be used to inform the party about lore, move the plot forward, assist an under-powered party, or my absolute favourite purpose – the double-crossing NPC. An NPC can perhaps fulfill all four purposes in the same campaign.

NPCs can be used to effectively build mystery, tension, and provide role-playing opportunities. I enjoy using them to have the players uncertain about whether they can trust this NPC and for how long. I use multiple NPCs so that there is uncertainty on whether this NPC can be trusted or will eventually double-cross them. Then sometimes after the NPC has gained trust and showed value to the party, they can backstab the party at the worst possible time. I have had a few players shout out “I knew it!” when the ultimate moment occurs.

Similar to Mimics and other opponents where their initial intentions are uncertain, the suspense and tension of not knowing if the NPC is a friend or foe is a great plot device to have the party discuss how they would like to handle the situation – “Can we trust the NPC?, should we trust the NPC?, should we set a trap to test the NPC’s loyalty?”

I know some Dungeon Master’s don’t like the DM playing an NPC, but I consider the NPC another part of the plot that the players have agency to determine how they want to handle the situation. The NPC isn’t destined to double-cross the party, it all depends on how the party deals with the NPC. Given the right actions, they could even convince the NPC to have a change of heart.

Ultimately, having subtle and complex encounters is much more interesting where not everything the party meets is immediately hostile. Giving the party the agency to determine whether to free NPCs and invite NPCs to join them places all the control with the players. As long as the DM remembers that the NPC isn’t a device to implement his/her preferred story, they can be an excellent way to introduce uncertainty, suspense, tension, and surprise.