I’m starting a new campaign in a couple of weeks’ time. I’m planning to use these four questions to rapidly develop my NPCs when I need to.
1. What does she want? Why? This question should be answered with half an eye to how this might intersect with what the PCs want. Is this a character the players might work with, or one who is likely to oppose them? But mostly, it’s about giving every major NPC something that they’re up to, so she isn’t just inert but in motion, or at least ready to move towards something. Why is important too, firstly because it dramatically changes how we feel about what she want, but also because it tells us a lot about what kind of character she is. So maybe she wants to take down the Empire, because they executed her brother; or maybe she wants the same thing because she hates the Emperor. (How do the PCs feel about the Empire?) Perhaps she plans to rob a bank because she needs the money to pay off her gambling debts, or perhaps she’s just greedy.
2. Who does he love? Is it true love, brotherly love, loyalty, or what? (Could be “what” rather than “who”, but that’s usually less interesting.) This is a separate question to 1, partly because it’s about who the character values without any need for a “why?”, and partly because it will often be the case that the character already has the person or thing that they love. (If they don’t, there may well be an overlap with the first question.) Again, we have half an eye on how this intersects with the PC’s interests – do they love or hate the person in question? The second part of the question helps to colour the question, which shouldn’t just be about romantic love but any positive relationship bond.
3. Who does she hate? Is this implacable hatred, rivalry, petty dislike or what? (Again, could be a “what” rather than a “who”.) Very similar considerations apply to question 2. Hate is great because it puts people at odds even when there’s nothing much at stake; they look for ways to hurt each other regardless. It’s somewhat interesting if the NPC hates the players, but probably more interesting when it’s a third person they have in common.
4. What will he do? How far would he go? In pursuit of his goals, his loves or his hatreds. This question tells us what the character’s immediate actions are going to be, and what his limits are. Immediate action is important for obvious reasons: it puts the character in motion straight away, makes them more than just a person you might meet. As for the character’s limits: Player characters are at their most interesting when they refrain from action not because they are incapable of acting, but because they believe it would be objectionable morally or emotionally. The same logic applies to NPCs. (Though a line the NPC won’t cross for simple practical reasons could also be important.)
Caveat: I think I’ve been thinking about these issues informally for a long time and used them in games without thinking, but this stuff is otherwise untested. Who knows whether I’ll still think they’re a good idea in three weeks! I’ll report back when I know.