Life of an NPC

GameMastery Guide, page 85

Once a GM knows what roles he needs NPCs to fill in a game and has a few notes about their specifics, its time to let the NPCs loose in the venue of an actual game. Transforming an NPC from an idea into an actual personality interacting with or facing off against the PCs proves one of the most challenging and rewarding aspects of any roleplaying game, often being one of the surest differences between a mediocre game and an extraordinary one. However, it requires not just a measure of acting talent but also fine judgment on the part of the GM to make an NPC feel like an active individual while avoiding common traps that such characters can present.

In this section

Building Connections In order to help the players see NPCs as actual characters and not just conveniences or cardboard opponents, the GM must work to build relationships.
Dead Ends Sometimes the death of an NPC leaves the player characters at a dead end, especially if the NPC dies before passing along some information that is vital to the progress of the adventure.
Who’s in Control? The term “nonplayer character” suggests that NPCs are characters played by the GM, but according to circumstances and GM preference, they might also be played by one or more assistant GMs, or by players whose characters…
Beyond Expectations Occasionally a throwaway NPC, one relegated to a limited role and with few expectations from the GM, comes to life, captures the attention and interest of the PCs, and grows into a campaign regular.
NPC Traps As NPCs make up one of the most pervasive and important parts of any campaign, they also present an opportunity for some of the greatest problems.