Give a sign = Suddenly she's surrounded by a ring of butterflies. But she thinks this could be something natural. Faith must come from within. (She loses a bit of faith, and possibly all of her devotion skill, which wasn't much to start with.)
Don't give a sign = ?

Even in VV1 there are hints of other inhabitants of Isola, either past or present; in particular the cave shows signs of being occupied, there is a ruined temple and statue, and so on.

In VV2 two villagers find the lost children. Where did they come from? Who were the adults who until recently looked after them? Were they decended from VV1 villagers who'd become separated from the tribe, other refugees from the volcano in their original home, or were they Isola's native inhabitants?

In VV3 they find a ruined city. Who built it and when?

In VV4 we concentrate on the Tree of Life. Who were the original people who cultivated it and lived nearby, though?

In VV5 we of course meet the heathens. Who were their ancestors?

Then of course we have Biggles. Where does he come from and how does he live so long? He first appeared in VV2 and is still around in VV5 so must be pretty old by now.

Accept=He/she is converted and joins your tribe
Send him/her back to their own tribe=?