Let people make their own decisions.
Most of us would probably think of a game like this as an imaginative exercise, involving fictional people that we make up, but people like those in the Fifth World understand an activity like this rather differently. They experience imagination as something that belongs to a particular place, which we get to participate in when we go there. They experience stories as persons in their own right, and the characters as other-than-human beings who know exactly what they want to say and do. Experienced authors often talk about their stories and characters in similar ways, illustrating how deeply this perspective runs in our unfiltered human experience. Try to accord the characters in the game such respect. Give them the opportunity to speak for themselves and make their own decisions. As much as you can, make yourself a conduit by which these characters can express themselves when you play them, rather than making their decisions for them.