To me, The Viewer is a predatorial and yet, territorial creature and entity. It's rules, seem simple. If sound is large enough to emit, alongside in physicals things that can see and spot the creature, it will detect it and aim to protect it's territory, or to eat. The caveat to this creature, is that it can only act to who is active, when that presence detects the creature.
A dual-way communication, similar to parasitism. And we can even see that with how the creature has two evolved forms. The first, resembling that of a stingray or a manta stingray without it's tail, will swoop down and like a stingray, scoop up what it can eat through the suction of the area around it. From then and there, it will then envelop and ensnare those who are within it's digestive tract, decompressing and suffocating the physical bodies but leaving the essence and the soul of those who it consumes. Be that animals or humans.
It can then use that essence as the souls are consumed by The Viewer, as a means to taunt those who try to defy it, and discard elements that it cannot decompose healthily. The second form, then expands and enlarges, becoming more like a giant jellyfish with it's tendrils now completely exposed, but it's mouth acting like a rattlesnake or a Venus flytrap. The method of this death would as opposed to being more lasting and more painful would be swift and quick. But it flaunts itself, revealing itself as a warning to those who would wish to defy it.