Add a sense of alienation to your metamorphosis stories and 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.
Story Design: Curse Stories covers all of the elements you need to prepare in order to tell a metamorphosis story. It’s based on concepts explored in Story Structure, also published by Dancing Light Press. It’s a big book that goes into greater detail on how to get the most out of the three-act structure, as well as developing a three-phase series (campaign, if you prefer) with a clear beginning, middle, and end. If you want to use your favorite roleplaying game system to tell stories with more depth than kill monster, get treasure, repeat (not that there’s anything wrong with that), it is worth looking into.