Appreciation and Wisdom
Appreciation for a friend, for nature, for a group…all these give an NPC depth as well.
Let's see an example of this in connection with another technique, Wisdom.
Here's the game scenario: You've been fighting slimy beasts on an alien outpost. The last one almost did you in. Your "health points" are just about down to zero.
You reenter the base. The Medic (male) looks you over, sizes up your beat-up condition, and digs a key out of a drawer. He hands it to you and says sincerely, "Want some privacy for a while? Here's the key to my quarters. Whatever you were doing out there, thanks."
In a small way, the Medic has exhibited insight (he's noticed your condition and deduced you were doing something heroic for the benefit of the group, which includes him). Insight is one of many forms of wisdom. It gives him depth. His statement also includes appreciation, another NPC Deepening Technique.
In more than one game, I've seen wisdom is dispensed by a "wise old man," usually a Gandalf type.
But having a "wise old man" who gives advice to the player can be a cliché. Thus, hopefully, if you do have someone old and wise, and they're a major and recurring NPC, you'll construct an original Diamond for them.
A perfect example was done a number of years ago in the first installment of The Matrix. The wise Oracle was spellbinding, because she had a great Diamond. In the movie, she is:
We see that she actually has four NPC Deepening Techniques placed among her five Traits:
Had she just been "deep" without having an interesting Diamond, she would have been a clichè and a bore. As mentioned before, "deep" is an option; "interesting" rarely is.
Although this book doesn't nearly have room for all the ways to give depth to an NPC, let's look at a few more.