The Metamorphosis by Franz Kafka (1915)

He wakes on his back, hard as armour, his thin legs waving helplessly above him, and his first clear thought is not terror but the train he is about to miss for work. Franz Kafka gives literature its most monstrous premise and then flatly refuses to explain it; the real horror is never that Gregor Samsa has become an insect, but that his family adjusts. Watch the love curdle into housekeeping: the locked door, the rotting scraps shoved under it, the sister whose violin he loved learning to flinch. This is the most exact thing ever written about being wanted only for what you provide, and about what remains of a person once the providing stops. Few books are so quietly unbearable about the small room you are kept in, the apple festering in your back, the morning they decide everyone would be lighter if you were simply gone.