??? Help! ???
Thanks for asking! We've been working on your question for a couple of days now, and I'm not 100% sure we've got the right fit, but I've got a couple titles I want to run past you to see if we can narrow things down. The best bet so far is Katharine Patterson's "Preacher's Boy", which has a young man, the son of a preacher in rural Vermont, who befriends a homeless girl named Violet and has some adventures that put him in conflict with his community. More info from Novelist. The setting is very different from the island environment we were thinking of, but you might take a look and see if it rings any bells.
Another thought is a book we don't actually have in the library's collection, but it's one of many tellings of the story of Queen Lili'uokalani of Hawaii. She was deposed from her position by a group of American profiteers called the Missionary Boys, spent some time in forced confinement, and in the James Houston novel "A Queen's Journey" her story is told from the perspective of a childhood friend named Julius, who might be the boy at the center of the story.
If those both strike out, let me know and we'll keep digging. By the way, do you remember when you first read the book or heard the story? Do you happen to know if it was a story aimed at younger kids, teens, or adults? Knowing those things will help us with further searching.