I can’t remember where I first ran across this idea, but I used it way back when I was running a D20 Modern campaign.
The basic idea is, before introducing a new NPC into the game, consider whether an existing NPC which the party has already met will serve. There are a number of advantages to this.
One of the main ones, in my opinion, is that it keeps the cast list for the game small. The fewer important NPCs there are, the easier time the players should have in remembering at least something about each of them. Hopefully.
Another advantage is that it keeps the players wondering. If each adventure has its own NPCs who never reappear, the player are likely to not care much about them or their motives outside of the obvious. When the NPCs start showing up in later adventures, especially if there’s no obvious link between the two adventures, at least some of the players are likely to be curious as to why this NPC has shown up again. It’s worth noting that you, as the DM, don’t actually need to have an explanation as to why the NPC is showing up again, if the players get curious they’ll start theorising. Just take the theory which you like the best and pretend that was what you planned all along. There’s a good chance they’ll be ecstatic that they figured out your plans and outwitted you. Just don’t tell them the truth 🙂
One last advantage, one I quite favour at this point in time: It reduces the amount of work the DM has to do. That’s always a good thing.
I took a slightly different approach for my Pathfinder game this time around. I basically went down the road I used to do for Vampire: the Masquerade and Werewolf: the Apocalypse, which is to document all the main players up front.
Now in those games, because of the supernatural aspect, the cast of characters is small, even in a big city. Not so in Pathfinder. Therefore, I decided to have the players centered in a hamlet rather than a city. It’s similar to the old Hommlet from the T1-T4 modules for AD&D1e (and subsequent reprints). I calculated every person who lives in the hamlet, which totals out at 44 when you include children. That number is manageable to at least give each NPC some details. If nothing else, the AD&D1e DMG has some great tables to generate some background.
It did force me to think about the role of each NPC, and to minimize overlap where possible. Also, as I considered each role, it helped determine relationships between different characters other than the obvious marriage and parent-child ones. If you remember the old V:tM City sourcebooks, it’s like the pictures with the arrows between various Kindred and a description of how they feel about each other.
It has certainly helped. This past session a PC’s unwillingness to be civil to an NPC had repercussions in the community, ones that logically fell out among the NPCs friends and benefactors. It forced the PCs to deal with their wayward child and smooth things over. That was a great spot of roleplaying.
My group’s currently running around the entire galaxy (Star Wars), so much less opportunity to do something like that, but I’ll keep it in mind if I go back to D&D or D20 Modern or something like that.