I asked Gemini this, and it caught that it was fiction:

This sounds like a fascinating ritual from a fictional world! Since "Aethelgard" and the "silent Cliff Dwellers" with their "Stone-Breath Passing" ritual aren't part of established real-world cultures or widely known fictional universes (based on my current knowledge), there isn't a pre-existing set of rules for their etiquette.

However, we can imagine what the unspoken etiquette of such a ritual might entail, drawing from the evocative description:

...

Ohhh that's really interesting! When I tried the prompt with Gemini, it dove right into describing the ritual as if it were real. Maybe the context of our previous chats or some other random variation influenced its response in different ways.