[Sorry for the delay between parts in this series. I had a couple of projects spring up unexpectedly that ate into my time and motivation. I'll try to be faster getting my next post out.]
Your campaign should revolve around the actions of the PCs, even when your campaign’s world does not. Anything that does not engage them is colour — something that adds depth and texture to your game, but has no real impact. In this spirit, any full NPC — as opposed to a character that provides colour — should affect the PCs’ lives.
The simplest way to ensure that an NPC has an effect is to ask, “What does this NPC want from the PCs?” If you make sure that you have a good answer for this and you play the NPC in a manner consistent with your answer, you will almost guarantee that the NPC will affect your PCs lives. The answer will also provide the core of the NPC’s role in the campaign, go a long way toward making the NPC interesting to your players, and provide clear guidance when you need to improvise the NPC’s actions. It can also drive conflict in your game.
When every NPC wants something from the PCs, and you actively play those desires, you create motion in your game. Whether the NPCs act in a way that forces the PCs to react, or the NPC’s desires clash with the previously established desires of the PCs, you are adding energy to the game. You are setting events in motion.
You are also leaving the players free to react in any manner they see fit. When you answer this question, you will establish an agenda for the NPC, not a plot or a series of set pieces. No matter how the PCs react to the NPC’s wishes, play can continue running smoothly with the NPCs pursuing their agenda in the most appropriate way. The NPC is not relegated to limbo if the PCs say “no” — or anything else — unexpectedly, either. The NPC can continue pursuing her agenda without interruption.
When an NPC wants something from the PCs, it also helps to draw the players into the game. Regardless of whether they decide to help the NPC or not, the NPC chose them, or is reacting to their efforts. There is an implicit message that they are competent, and even important, which always feels good.
When the NPCs maintain their agenda, but must adjust their plans to account for the PCs’ actions, it establishes that the PCs are having an effect on the world around them. This encourages the players to be more proactive. Whether this is more fun for them or not is a matter of taste, but proactive PCs make the job of GMing easier. Suddenly, the burden of providing momentum to the game is shared among all of the players, taking some of the load off of your shoulders.
The fun in any role-playing game comes from drawing the PCs into a conflict, and then watching them PCs fight to return to safety or normality. You can even look at the iconic dungeon crawl as a struggle between characters that want to become rich and powerful on the one hand, and the monsters that stand in the way of the treasure that will get them there on the other. With that in mind it shouldn’t be too hard to understand that NPCs are useful tools for drawing the PCs into conflict. I would even say that the line between a real NPC and a colour character is whether the character plays, or can play, a meaningful role in a conflict that involves the PCs.
Therefore, when you decide what an NPC wants from your PCs, you should choose desires that create conflict for the PCs. If the PCs have established goals that they are pursuing, the NPCs should be pursuing agendas that will oppose the PCs goals, coincidentally make it harder for the PCs to achieve their goals, or lead the NPCs to aid to the PCs. When the PCs do not have established goals, the NPCs’ agendas should draw the PCs into conflict.
The potential conflicts have to be interesting enough to the players that they are drawn into them, of course. Not every character with an agenda needs to be a full-fledged NPC, either. Every RPG bartender wants PCs to spend large amounts of money in his tavern. Unless the PCs are likely to end up in an interesting conflict because of the bartender’s desire — putting the PCs in the bar may serve as a good backdrop for introducing other elements of the story — the bartender’s desire is colour, not an element that drives conflict.
Just as a final note, “I want to be left alone,” and similar agendas can be interesting, but only if other events are likely to cause the PCs to come into conflict with it. If the PCs never encounter the loner, there is no conflict. If the PCs have decided that they need information that only the antisocial NPC has, however, you have conflicting agendas, and a possible source of fun.
Why and To What End?
Typically, it is a good idea to go a little beyond just what the NPC wants from the PCs. While the campaign revolves around the PCs, going beyond what the PCs will experience just a little bit can create depth, and can help you handle situations where the players leave the reservation, so to speak.
Asking “Why?” the NPC wants what she does from the PCs will typically give you the NPC’s broader agenda. Knowing this can help you develop allies and enemies for the PCs, give the PCs ways of striking back at an NPC that has upset them, and provide avenues for future sessions.
Asking “Why?” again about the NPC’s larger objectives is generally a waste of time unless you want to play a true melodrama, though. It usually leads to psychological analysis and answers like “her daddy didn’t love her enough.” If a complicated plan is part of the NPC’s concept — say your average megalomaniacal villain, for instance — the first iteration may just scratch the surface, and going further is a good idea.
Asking “To what end?” will typically lead to the same things that asking “Why?” does.