Story structure
Anagnorisis
The moment a character makes a critical discovery, Aristotle's change from ignorance to knowledge, often firing the reversal.
Anagnorisis is "a moment in a play or other fictional work when a character makes a critical discovery." From the Greek for recognition, it was narrowed by Aristotle in the Poetics to "a change from ignorance to knowledge, producing love or hate between the persons" destined for good or bad fortune. Aristotle valued it most when it fires the peripeteia at the same instant, the double turn he called the mark of a superior, complex plot; Oedipus learning the truth of his parentage is the type case. Modern examples run from The Sixth Sense to the reveal of Darth Vader as Luke Skywalker's father in The Empire Strikes Back.
Reveals are the highest-value beats a long story has, and this is the term for the internal ones: the discovery changes the character, not just the reader. Plan what each character knows and when; see character secrets and reveals.