The Inverse Hierarchy of Voice Trickery

Inverse voice is a kind of agency hierarchy. In English we're used to being able to say by the, you know, right, we can give the agent of a passive sentence. But it's sort of marks. It's some obliques in some weird case or a prepositional phrase. The inverse doesn't demote it in the same way. It just moves it around. Why do we do this? Because we either want somebody else to be moved to the front of the sentence or we have some grammatical restrictions that we have to satisfy. If you can only have nominatives as the head of a relative clause then you might need an inverse in either the matrix