Do you have "secret shortcuts" for grokking the way to roleplay particular concepts?

Sometimes we, especially as Referees, roleplay people we've got a hard time understanding with our usual logic (whether it's elves in Glorantha, or Fair Folk in Exalted, or inquisitors who are genuinely concerned about their victims...)

So, how do you go about it?

My example is the Fair Folk in Exalted. My secret is that I model them after "dirtie hippie storygamers playing a traditional game and trying to get their schtick to apply".

Yes, the Fair Folk are the guys and gals who pick a genre and try to behave like the heroes and heroines. And expect the game to accommodate them by inserting the tropes.

And are then disappointed when my NPCs seldom do.

What are your secrets?