I'm thinking more specifically of relatively isolated groups. For example, in The Thin Red Line, the indigenous people of Guadalcanal are shown guiding the American troops. Why were they on the American's side or were some simply on that side? Did the two sides have opposing methodologies for recruiting them?
Did the people of different areas relate to the opposing sides in different ways?
I do not know much about the general Pacific theatre, however I do know about the Kokoda track and the conflict there. When it comes to the treatment of the indigenous people there it can only be described as abhorrent.
The indigenous people were often shang-haid and used to carry equipment and supplies and were punished with execution and beatings. Reports of being imprisoned and held captive in cages(by Australian forces) even if the Fuzzy Wuzzy Angels volunteered due to a fear that they might betray the position of Australian troops. If they did not help or were aiding the enemy then villages were burned.
This lead to the indigenous people swapping allegiances whenever the opposite side captured their village. The indigenous people were simply a tool to use, not something that was of particular value.