A·nag·nor·is·is

A moment in a play, story, or other narrative where a character makes a critical discovery or recognition

Often realizing a previously unknown fact about their identity, situation, or another character that changes the course of the story.

"In Oedipus Rex, the protagonist experiences an anagnorisis when he realizes that he has unwittingly killed his father and married his mother."

From the Ancient Greek ἀναγνώρισις (anagnṓrisis) meaning “recognition” or “discovery,” from ana- (“again”) + gnōrísis (“knowing”).