There's a rather wonderful Youtube channel called Overly Sarcastic Productions that talks about storytelling. I almost wholeheartedly recommend it – other than the main woman sometimes seems to lend the channel to her boyfriend who is much less personable and much less interesting.
Anyway the last time I had anything to do with the novel "Watership Down" was in the 1970s. My dim childhood recollection is that it was both very hard to understand and very very sad. However now that I've heard OSP talk about it, I might have to put it back on my reading list. She puts it in a category almost all by itself called "Dramatic Irony Cosmic Horror" and I think she's right.
Dramatic irony is when we as the audience know something about the story that the characters don't. We know there's a hungry shark under the waves and we can hear it ominously playing the cello (I think) but the woman swimming doesn't know it's down there. We know that the dates have been poisoned, and we don't want the hero to eat one, but the characters haven't seen the telltale poisoned monkey yet.
Cosmic horror is when the main point of the story is that it's a cold, unfeeling and unfathomable universe that we live in.
Watership down is about a group of rabbits that get poisoned and their warren dug up. For us it's dramatic irony because we understand housebuilding, and we know what trains and cars and things are. For the rabbits its senseless, arbitrary and cruel.
OSP says it's like reading Colour Out of Space if we were the Eldrich abominations. "Oh yeah that makes sense, that colour (never before seen on earth) would be very bad for biological life there"
Richard "The Cello is Non-diagetic" B
