Perhaps a tricky plot or plot element since the main character is the victim of a curse. The prince who is turned into a frog is a classic of this kind of story. Here the main character falls under a curse. I've used this plot device once. In the Amber Dragon written as part of an anthology and part of "The Amber Chronicles." In this case, the vain princess has been spoiled by her father who wants her to marry but she hasn't chosen anyone. Into their lives comes an evil magician sho wants to marry the princess and rule the kingdom. The princess is cursed to become a small, fat amber dragon. She must receive the kiss of a prince to change her back. Unfortunately the princess has been nasty to every prince in the world. The problem is of course solved by a stray prince but not without the princess learning a bit about life and love. Hear there is a happy ending.
A happy ending isn't necessary and some of these stories end unhappily. This is a device often used in fairy tales which is where my idea arose.
What is needed here is a character perhaps with a lesson to be learned. A curse and not necessarily done by an evil person that changes the character into an animal. The character may or may not learn the lesson being taught.
This kind of story can be fun to write particularly as an experiment. For me the bits of humor were what kept me writing to the end. How does a dragon get a prince to kiss her after she's found the only prince available to her.