Who is Yae from Peace Child and what is their importance?

The book opens with the story of Yae, a native Sawi who lived and died in the jungle before the arrival of any Tuans. He begins what he believes to be a peaceful treaty with a neighboring village. After months of meetings, however, the new friends turn on him. They tell him, just before they kill him, that they fattened him with friendship for his slaughter, a practice called tuwi asonai man.