Not appropriate for a 12 year old, but the Tethered in Us are a very clear allegory to imperialism to me. The most common interpretation I heard when that movie came out was that each characters’ Tethered represented repressed aspects of themselves, which is clearly true. But in a literal sense, they are people who have suffered as a direct result of the main characters’ comfortable lives. Their comfort and wealth is enabled by the existence of The Tethered.