You need a hard-edged line for a character discovering morality as damage: conscience framed not as redemption but as a malfunction in a machine built for a crueler purpose.

Foyle treats the arrival of a conscience as an infection, and Bester lets him be right: it is fatal to the revenge machine he built. The moment he can feel what his torture of Kempsey actually was, the tiger's operating system crashes. It's the book's bleakest joke and its real turning point: becoming human is diagnosed as a terminal condition.