Why does Perry go on a hunger strike? Why does he eventually change his mind and end his hunger strike?

Perry has stopped eating, and spends the summer in the prison hospital, connected to a feeding tube yet still refusing sustenance, determined to take his own life before it can be taken from him. One afternoon, however, he receives a card from his father, addressed to the warden, inquiring about his son; the card inspires a frenzy of “love and hate,” and Perry resolves to end his fast and return to the world of the living.