The OCEAN theory of personalities gauges five criteria:
- Interest in new ideas or different points of view.
- Placing value on doing what needs to be done.
- Attraction to other people and social situations.
- General likability, without implying leadership quality.
- Susceptibility to emotional hurt.
I have no idea whether this is even remotely scientific (although it seems a heck of a lot more plausible than Meyers-Briggs), but it occurs to me that you could use these to cobble up NPC personality types using a 2d6 scale and rating each aspect from two to twelve. If an event occurs (a PC-NPC interaction, for example) that looks like it would strain or test one of these aspects, roll 2d6: if the result is under, the NPC behaves according to the definition of the aspect. If it is over, they violate that behavior.
When rolling for a quick personality, however, it makes more sense simply to set three aspects at seven (not outstanding one way or the other), and select two to be Roll 1d5 to get first aspect, then 1d4 (and skip the one you already selected) to determine a second aspect. For each, determine if this aspect is high or low. Since average aspects are, well, average, you'll want to come up with a different distribution for the other two.
A neat co-incidence appears when you take away the three middling values of a 2d6 roll (6, 7, and 8): there remain exactly twenty dice combinations. Ergo, you can roll 1d20 for the two aspects, and consult the following chart:
A result of 2 through 5 is Low, 9 through 12 is high. 2 and 12 are extremes, but the following charts only take into account whether the result is Low or High.
High - High correlations:
Low - Low correlations:
High - Low correlations:
Low - High correlations:
This gives us the following 40 possible traits:
- Pleasant when engaged with, but not seeking attention.
- Easy to get along with, dislikes conflict.
- Not necessarily hateful, but doesn't like people.
- Doesn't seek company of others; is likely to take offense at imagined insults.
- Blames everyone for his/her problems; causes most of them.
- Has firm ideas and tries to enlist others to enact them.
- Engaged, to the limit of their intellectual capacity, with others' ideas.
- Likeable, if not inspiring. Can be a clown, or a true leader.
- Dislikes people; tries to assert dominance by hurting others.
- Fascinated by philosophies, but has firm ideas of his/her own.
- Unafraid of hard work and long study.
- Tries to sway others to his/her point of view, tries not to be swayed.
- Hard-working, resentful of those who look like they're having a good time.
- Centered on a goal. Does not stray far from that center.
- Able to see and feel others' ideas and emotions.
- Will agree to things that others say, but not stay true to their ideas.
- Down on the world, and the people in it.
- Up on the world, and the people in it.
- Tries many things, rarely if ever sees a project through to completion.
- Like Driven, is centered on an idea, but may not know why.
- Loud at gatherings, but quick to take offense.
- Sees the world of people mostly from the outside.
- Sees the down side of everything. Thinks they're doing people a favor by this.
- Sees manners as a way to grease the wheels of social interaction.
- Willing to get into fights just to prove some ephemeral point.
- Thrill-seeking. Wants an audience, or co-conspirators.
- Doesn't like people asking questions about them. Their secrets are usually petty.
- Mindful of own business, and persistent at it without getting heated up.
- Keeping to oneself.
- Wildly romantic and imaginative, but prone to mood swings.
- As untrusting of others as others should be of them.
- Like driven, but less focused on action and more on simple faith.
- Likeable, but slick.
- A yes man, but not trustworthy.
- Willing to take from others, and living by an obvious double standard.
- Wants to be liked. Agrees to anything as a result.
- Says whatever's on their mind, even if inappropriate.
- Tries to be self-sufficient; may or may not succeed.
- Friendly one moment, ready to snap the next, something else the next.
- Sees no value in people who don't agree with them; never sure what they really think.