Nastiest story I've ever read

I don't mean to be too much of a sentimentalist and I know that good people can write stories about evil people and evil behavior - and yet - what are we to make of V.S. Naipaul's almost unbearably nasty story The Heart in his collection A Flag on the Island? The story is about a sickly young boy whose parents buy him a dog in hopes that this pet will bring out good qualities, help him socialize and overcome some of his fears. Essentially, the story recounts in gruesome detail the boy's attempt to "train" the dog to love, obey, and fear him: he absolutely brutalizes this poor confused little pet - like the worst possible sadistic torturer. He's really nice and kind to the dog, that kicks and whacks him. Sure the story is well crafted and his a weird little twist at the end - I'll give it away because I don't even want to suggest that you read this story - the boy's father drives over the dog, and there's a hint that he does so in order to put an end to his son's cruel behavior toward the pet. Great way to deal with the problem, huh? I just have to wonder what kind of mind could even set out to write a story like this; why would anyone want to think about this kind of behavior, much less chronicle this behavior, without its being part of a grander scheme or purpose. Nastiest story I've ever read. Most of Naipaul's A Flag on the Island is the title story - a novella, really, which recounts a return visit to Trinidad by an American GI (from WWII) and, in a somewhat surrealistic account of three days or so of drunken revelry as he visits people from his past and sees how they, and the island have changed. It pushes the edge of credibility, but in its antic tone and quick cuts of scenes it falls in the tradition of Cane and Master and Margarita, two other challenging works that incorporate a wide range of styles and moods in a short space and that bring literature pretty close to the style and pace of narrative cinema.