You want a single sentence that marks a character's irreversible transformation; or you need to show a turning point as instantaneous compression rather than gradual growth.

The moment the Vorga passes Foyle by, the old cipher is annihilated and a new creature ignites. Bester compresses an entire metamorphosis into a single sentence: betrayal as a birthing force. Foyle doesn't decide to change; the acid of fury changes him. Revenge here isn't a motive, it's a manufacturing process that builds a machine out of a man.