Trying to find some kind of pose reference was strangely difficult today, couldn't find the right things anywhere. However, Derek got me looking into an artist called Saul Steinberg to get a different perspective on using symbols and marks instead of actual words for the abuse (and nicer things) being hurled into the hole. Here's some of the works that I thought were relevant to the theme.
I found more images here but I'm prevented from sharing them, so you'll have to check them out here yourselves. Sorry about that.
Another artist I found completely by accident today is Beksinski, a polish artist whose work reminds me of a mixture of Francis Bacon, Giger and a dollop of surrealism.
(click for full size)
I saw this piece-
-and the skinny, stretched limbs really struck me, so I looked for similar pieces he'd made.
I don't intend to make my animation in this style because that would be bonkers, but I'm tempted to do a piece of concept art on a similar style to make it look as grim as possible.