A successful twist leaves the reader convinced they should have seen it coming. That reaction is engineered, and it depends on information the author showed rather than hid.
Concealment and misdirection are different techniques
Withholding a fact until the final chapter produces surprise but not satisfaction, because the reader had no opportunity to reach the conclusion themselves.
Misdirection shows the fact and gives the reader a reason not to attend to it, which preserves the possibility of having worked it out.
The distinction is what separates a twist readers admire from one they resent, and reader reviews of thrillers return to it constantly.
Attention is directed by apparent importance
Readers weight information by how the narrative frames it. A detail delivered during a tense scene is remembered; the same detail mentioned in passing during a quiet one is registered and set aside.
Authors place decisive information in the second position, present but unemphasised, often surrounded by material the reader has been trained to consider more urgent.
Nothing is hidden. The reader's own sense of relevance does the work of concealment.
False explanations occupy the space
A reader searching for a solution will accept a plausible one and stop looking. Supplying that plausible answer early is more effective than supplying none.
The alternative suspect, the reasonable motive and the apparently confirmed alibi all serve this function, absorbing the reader's suspicion until the real answer is revealed.
This is why the strongest reversals feel like a reinterpretation of what was already read rather than the arrival of new material.
The reveal has to be verifiable
Readers frequently return to earlier chapters after a twist, and a reversal that does not survive that check is judged a cheat.
Authors and editors therefore audit the manuscript backwards, confirming that every clue is present and that no statement contradicts the final explanation.
Narration is the usual failure point, since a first-person narrator who knew the answer throughout must never have thought about it on the page.
Genre expectation raises the difficulty
Experienced thriller readers arrive expecting a reversal and actively searching for it, which means the techniques have to work on an audience that knows they are being used.
The response has been escalation, with multiple reversals and unreliable narration, and each escalation trains readers further, which is why the genre's structural conventions keep moving.