The working definition
A reveal is a disclosure of a fact the reader lacked that changes the reader’s understanding of what she has already read. The definition has two parts, and both are needed. The first separates a reveal from ordinary new information: most of what a novel tells the reader is new, and most of it changes only what will happen next. The second makes the reveal retrospective: after it, earlier passages mean something they did not mean before, and the reader’s mind goes back over them. A pistol produced in the last chapter is new information; the discovery that the narrator fired it in the fifth is a reveal.
The retrospective movement is what the chapter calls the double reading. Every passage that bears on a reveal is read twice, once forwards, under the reader’s understanding at the time, and once in memory or on a second pass, under the understanding the reveal supplies. The first reading is the one the reader made; the second reading is the one the reveal makes. A reveal is prepared when the passages before it support both readings, and the craft of preparing one is the craft of writing sentences that are true under each.
The fact disclosed may be large or small, and the reader may or may not have known there was something to learn. What makes it a reveal is the change of understanding, not the size of the fact or the reader’s surprise. The disclosure may come by a character’s discovery, by a document, by a change of narrator, or by the narration itself; and it may be shared with the characters or reach the reader alone.
Adjacent terms
A recognition is a character’s change from ignorance to knowledge, Aristotle’s anagnorisis. It is the reveal received on the page. Oedipus learns who he is; Pip learns who his benefactor is. A reveal can occur without a recognition, when the reader alone learns a fact (the last pages of a novel told by a murderer), and a recognition without a reveal, when a character learns what the reader has known all along. The two coinciding is the strongest arrangement and the commonest.
A twist is a reveal the reader did not know to expect, the popular name for what this chapter, following Meir Sternberg, calls a surprise reveal (see How It Works). A clue is a passage that bears the second reading for a reader who looks for it, and a red herring is a passage built to support a false second reading; both are tools of the double reading, described in The Mechanism. Dramatic irony, in The Viewpoint Shift (Chapter 13), is the reader knowing what a character does not, and the reveal is one of its ends: the moment the character catches up. Paralipsis, Genette’s term, is the omission of information the narration’s own vantage ought to have supplied, the mechanism of most reveals and of most cheats, and The Transition (Chapter 5) and Backstory and Flashback (Chapter 7) use it for the false ellipsis and the withheld past. A plant, in The Ending (Chapter 16), is an element deposited early for use late; a reveal’s preparation is a set of plants whose second meaning the reader did not see.
What the chapter leaves to other chapters
The mechanics of narrating a past event once a reveal has made it necessary, the cutaway and its registers, belong to Backstory and Flashback (Chapter 7); a withheld past disclosed late is this chapter’s. Truths withheld by the arrangement of two or more timelines, where the reveal is a convergence of times, belong to Non-linear and Multi-timeline Architecture (Chapter 8), which this chapter touches only where the withholding needs a reason. The prologue that discloses its ending in advance belongs to The Prologue (Chapter 10); the midpoint that turns on a revelation is placed in the book’s shape by The Middle (Chapter 11), and this chapter says what the revelation must do once it is there. A character’s change of the rule by which she chooses is an arc, in Arc and Theme (Chapter 12); a change in what the reader understands is a reveal, here, though the two often fall at the same moment. Who may know what, and at what cost to the book’s allocation of minds, belongs to The Viewpoint Shift (Chapter 13); the ending’s other duties belong to The Ending (Chapter 16); and a reveal held across volumes of a series, or required by a genre’s contract, belongs to Series and Genre (Chapter 17).
See also: the full treatment, section 1, on the boundary between a reveal and a recognition.