Been lurking here for weeks looking at amazing builds, hard earned feats, funny moments, etc etc.
I was playing with my brother earlier and a (somewhat?) simple feature occurred to us as we gathered resources on the edge of a tree line at dusk. When you're in that atmosphere, you constantly scan for anything incoming, anything sinister – we mutually agreed at that moment that it would be so cool if occasionally at dawn, or dusk, when you scanned a forest, or the water, you'd see a large set of eyes stare back, maybe even a figure of imposing size, and it would just watch you. Perhaps rarely, maybe 1% of the time it would do something, throw an object your way, take steps toward you, dash between trees.
In the case of the ocean, it would rest at the surface and just watch. Occasionally in this case you'd see a dark figure move under your boat, of obvious enormity. I'm not necessarily suggesting these are to be interacted with, at-least not initially. But serve as the manifestation of the greater danger that is so prominent in the world to give the greylings the night off.
I have no further ideas as to what these things would be, what lore or creature they'd take on. Just that they're there, and they watch, and reinforce that the living feeling the world has at these hours of the day is there, watching, lurking.