Honestly, I kinda stumbled into this niche by accident, scrolling through forum threads that were way too specific. From what I've pieced together, the themes tend to orbit around a few core ideas. There's a huge emphasis on total power imbalance, obviously—this massive, often indifferent creature and the sheer helplessness of the smaller character. It's less about the...erm, consumption...and more about the psychology of being utterly overwhelmed, of being reduced to insignificance.
You also see a lot of 'accidental' scenarios, like someone falling into a pool or enclosure, which plays into that fear-turned-fantasy of a careless mistake leading to an inescapable fate. The setting is often a zoo or a natural habitat, making it feel almost plausible in a twisted way. I think the appeal for readers is less about romance and more about exploring extreme vulnerability in a safe, fictional space. It's a very particular kind of catharsis, really.