From publisher blurb:
How can you add more character-driven action and a sense of alienation to your metamorphosis adventures?
Story Design Volume 11 - In a curse story the antagonist feels that the protagonist has done something wrong. Maybe they have, and the antagonist’s actions are justified; maybe they haven’t, and the antagonist’s wrath is misplaced or unfair. As a result of the antagonist’s need for justice, the protagonist is physically changed somehow. This does not have to be a literal curse; the changes can be the result of magic, medical experimentation, genetic manipulation, poison, radiation, or whatever else fits the genre, time, and place. The changes may offer some advantages, but they also bring significant drawbacks, and the protagonist will want the effects to be reversed.
Examples of the curse plot include Beauty and the Beast, District 9, The Fly, The Metamorphosis, Pinocchio, Thinner, and The Wolfman.