I was reminded of the moment, many years earlier, when the flag of the Portuguese king was hoisted over the fortress tower in Azemmur. I had been only a young boy then, but I still lived with the humiliation of that day, for it had changed my family’s fate, disrupted our lives, and cast me out of my home. Now, halfway across the world, the scene was repeating itself on a different stage, with different people. So I could not help feeling a sense of dread at what was yet to come.
-- Mustafa (Chapter 1 paragraph 31)

Importance: Mustafa is able to relate to the Indians throughout the story because his enslavement mirrors the situation that they are in when the Castilians invade. This is what lets the expedition survive though because unlike the others, he’s able to communicate and form alliances with the different tribes they encounter.

As for me, my bondage had...
-- Mustafa (Chapter 1 paragraph 39)