Cultural Difference that I stumbled upon...
I was astonished by how differenly time and place affect outlook on a single subject. The way that the spaniards in the 18th century treated the native Americans, the enslaved native Americans (who were called neophytes), and mixed blooded Spanish-Native Americas is so vastly different, it's hard for me not to be negatively biased about the conversion of the natives to Christinity, or the enslavement and sometimes downright murder of a people who were so peaceful. The Spaniards, as with most nations who colonized around the 18th century, paid no heed to the grievances of the native people, and thus, the outcry became an ignorable whisper. In modern times, anti racism laws prevent most cases of outright bigotry, and the 18th century Spaniards could learn a thing or two from them too!

In terms of other responses to the story so far...
So it turns out that the life of a half Native American, half Spaniard is anything but boring. The quote that gives the most significance to what I'm feeling here is: "In the meantime, Ana, with her habitual good nature, had taken Regina's child, whimpering with hunger, to her breast; thus Diego and Bernardo, Ana's son, began their lives with the same milk and inthe same arms. This made them milk brothers for as long as they lived." So our main character, Diego, is born to a mother who cannot feed him straightaway. This results in a friendly bit of compassion on her friend, Ana's part, when she takes both her son and Diego to her breast. I don't know what sort of significance this has to any sort of theme, but I thought it was interesting. This 'milk brother' bond holds out too through Bernardo and Diego's youth. While Bernardo, supposedly fully Native American is subject to (and accepts) scorn and resentment, Diego, being the son of a Spaniard, goes to school, learns to fence, and gets respect. Together, Diego and Bernardo learn together what it means to be brothers and also, they learn to face a world full to the brim with hatred for people like Diego's 'brother'.