The slave isn't who you might initially think. The setting is based on an Avatar world with no Avatar but all the bending intact. Each of the four nations has its own language (sometimes more than one!) and culture, and the story takes full advantage of it by following the trials and tribulations of the captured slave forced into a completely alien community. There's a little Dances with Wolves
flavor here, but it's not as one-dimensional. And if world-building isn't your thing, there's plenty of cute Zutara moments.