Including this character is a must as she does appear in the source material (and I'm trying to be faithful about character inclusion), but her appearance is so minimal I have no grasp on her personality, attitudes, culture, etc.
What I do know: She's Cheyenne (Tsitsistas), she's 18 years old now, having spent the last four years at a specialized school (with children from a variety of backgrounds, though most are white), and the school is as culturally sensitive as it could be. The special nature of the school doesn't impact this question so much--that I can research, actually. She grew up with both parents, and has a close relationship with her maternal grandfather.
What I don't know: Based on any one of the three potential backgrounds for her (no reservation background, Northern Cheyenne, Southern Cheyenne--and yes, I'm aware they might differ greatly in some areas), in what ways would her culture/outlook on various things be similar or different to mainstream US culture? In other words, how likely is it that I should treat her as "the same as any other teenager" with regards to her thoughts or interaction except for a few areas, vs. having her react/interact very differently from the others her age? (Other students her age at the school are from varying US subcultures, mainly urban/suburban white.)
Also, in what areas would the school have made special arrangements for her, if any?
These questions are very open-ended, precisely because I don't "know" the character yet. I can't picture her because I have no experience with her culture. If you have any input, even if it's just "here's a story (preferably freely available online--fanfics are great for that) involving a Cheyenne girl that might give you a base to work from", that would be awesome. If you're only familiar with one of the three potential backgrounds, still awesome! I haven't decided yet which way I will go with her background, and it'll probably be decided by whatever information I'm able to get. Unfortunately, simply reading a "here's info about the tribe" page isn't going to help me picture this character, which is the real trouble; I'm not half bad at general research. Any info you can give, particularly any personal knowledge or experience, would be very helpful. While she's not a main character, I'd like to make her inclusion realistic (probably more realistic than the source material, even).
Edit: I did come up with a few more specific questions, thanks to all the probing--sometimes it just takes me a bit, thanks for your patience!
First off, what is the pattern of migration on/off the reservation? Do most people, once on it, stay on it all their lives, or is there a lot of transience? What factors affect someone's leaving--personality, financial, other? I'm trying to come up with a plausible reason for her parents to have been off-res for her birth (quite a distance away, actually), why they would have returned so she would grow up there, etc. Also, what would be her attitude towards leaving it for the school? Would she only do it because her elders told her to, or would she likely be curious and interested in going?
Also, given she spent a lot of time with her maternal grandfather, what sorts of things would he have taught her? What would they have done together?
The aspect that I most need to iron out is how she would interact with the other (mainly White, though one's Asian) students her age. How much of an effect does personality versus culture have on her spending a lot of time with the others? Is it likely that she would be somewhat aloof, or keep to herself more? Would there be any cultural aspect that would involve her attitude towards the others, either the ones her own age or the ones several years younger? How much of a bond would she have with another Native American (Indian, if one prefers that term, as it seems some do) from another tribe, just because he's also Indian (and would it depend on which other tribe?), or would it be more affected by personality, gender, or age? (the other two Native Americans at the school are boys a year or two younger than her, and not from the same group--several states away, rather, very different nation)
And finally, if she were raised with traditional values (presumably from spending much time with her grandfather as well as her parents, from the bits of background knowledge that already exist for her), what would be her attitude towards violence, such as self-defense or attacking someone else before they can attack you? How much of an in-community agreement is there with regards to how one handles hatred? revenge? crimes that cannot be brought to proper justice? (I'm kind of wanting to know how much leeway I have in constructing her viewpoints in these areas.)
Are there any spiritual aspects that I would need to take into account with regards to her everyday or weekly habits?
Thank you so much!