What the Midpoint Does
The midpoint is not a pause. It is a shift in the story's direction, stakes, or nature. The story after the midpoint must feel different from the story before it. This shift is the midpoint's only job, but it must do that job unmistakably. Readers feel the midpoint as a gear change: the sense that the story has moved into a higher or lower register, that the rules have changed, that what the protagonist is doing now is different from what they were doing in the first half of the second act. Without that gear change, the middle is a single sustained note and readers begin tuning out.