Maybe in the fanfiction, the Fairy Godmother has a change of heart after seeing the love between Shrek and Fiona. She then decides to use her powers to protect their relationship from other threats, like an evil wizard who wants to break them apart. She would have to use her wits and magic in new ways to keep them safe. This could involve her creating magical barriers or disguises for Shrek and Fiona when they are in danger.
In a fanfiction, the Fairy Godmother could be a time - traveler who has seen Cinderella's future and is determined to change it for the better. So she intervenes in ways that are not in the original story. For example, she might teach Cinderella self - defense skills so that she can protect herself from her stepmother's abuse. Or, she could bring in other fairy - tale characters to help Cinderella, like Little Red Riding Hood who could offer her some advice on how to deal with the big bad wolves in her life (metaphorically speaking, like the mean people in the kingdom).
Maybe in the fanfiction, Shrek and Fiona are both actors in a play about their ogre selves. As they rehearse, they start to have real - life feelings for each other. They have to deal with the public's perception of their on - stage characters while exploring their new relationship. They might go through funny moments like when Shrek accidentally breaks a prop during a romantic scene, and Fiona can't help but laugh, which makes their bond even stronger.
She could be made more sympathetic. Instead of being a villain, show her backstory of how she got into the business of trying to control others' lives. Maybe she was forced into it by some greater power, and in the fanfiction, she could break free from that control.
A great Shrek crossover fanfiction idea is to cross him over with the Lord of the Rings. Shrek could be mistaken for an orc at first, but then prove his worth to the Fellowship. He might use his ogre - like abilities to help them on their journey, like his strength to carry heavy loads or his sense of smell to track enemies. Another could be a crossover with the Matrix. Shrek suddenly finding himself in the digital world of the Matrix would be quite the shock. He'd probably just barrel through the agents with his brute force. Also, a crossover with the Incredibles would be fun. Shrek and the Incredibles teaming up to fight a common enemy would be an action - packed story.
One idea could be to create an OC who is a long - lost relative of the Scary Godmother. This OC could have been hidden away in a different magical realm and now returns, causing a stir among the existing characters. They could bring new magical powers or a different perspective on magic that challenges the status quo in the Scary Godmother's world.
One idea could be that the reader is a lost traveler who stumbles upon Shrek's swamp. Shrek, being the gruff but kind - hearted ogre he is, decides to help the reader find their way back home. Along the way, they encounter various fairy - tale characters and have to work together to overcome obstacles. This could involve things like outsmarting a tricky witch or helping a giant who has lost his way.
One idea could be a story where Shrek and Fiona take a trip to a far - off magical land they've never been to before. They encounter new and strange creatures and have to use their wits and each other's strengths to get out of various tricky situations.
One idea could be that Lord Farquaad somehow returns from the dead but has lost his memory. Shrek, instead of seeing him as an enemy right away, decides to help him regain his memory. Along the way, they discover things about each other that they never knew before.
One idea could be a fairy who has lost her magic and has to go on a quest to find it again. She might encounter various magical creatures along the way that either help or hinder her.
One idea could be that Natsu discovers a new and rare type of fairy magic that he has to learn to control. Another could be Natsu getting involved in a fairy war and having to choose a side. Maybe he could also meet a fairy who has the power to grant wishes and he has to decide what to wish for.