One idea could be exploring Ardyn's backstory in more detail. Maybe show his life before he became the villain, his relationships, and what led him to the path he took. Another plot could be a redemption arc for Ardyn, where he has a change of heart and tries to make amends for his wrongdoings.
Luna would be an interesting character to pair with Ardyn. Given her connection to the Astrals and Ardyn's complex relationship with the divine, they could have some deep and meaningful exchanges. It could also explore how Ardyn views Luna's role in the events of the game.
One plot idea could be exploring their relationship before the fall. Maybe a story of how they met and the initial attraction. Another could be a what - if scenario where Aera manages to save Ardyn from his dark path. Or perhaps a fanfic set in an alternate universe where they are able to live a normal life together, away from the chaos and tragedy of their original story.
One idea could be exploring the backstories of the minor characters in more detail. For example, the merchants in the game might have their own adventures before arriving in the main cities. Another could be a 'what if' scenario, like what if Ashe had made different decisions during her quest for the throne. A third idea is to focus on the relationship between the characters outside of the main storyline, such as how Basch and Gabranth interacted when they were children.
One idea could be a story where the Mandalorian has to team up with an old enemy to fight a new, greater threat. Maybe a powerful Sith Lord emerges and they have to put aside their differences.
One idea could be exploring a different origin for Toothless. Maybe he was part of an ancient dragon tribe that was thought to be extinct. Another could be a story where Hiccup discovers a new dragon species that has unique abilities and forms an alliance with them. A third idea is a time - travel fan fiction where Hiccup goes back in time to prevent a great dragon war from ever starting.
A great plot for Warframe fan fiction could be a Tenno getting trapped in a parallel dimension where the rules of the Origin System are all messed up. They have to find a way back while dealing with strange versions of familiar enemies. Or perhaps a story about a Tenno who discovers a hidden Orokin vault that contains not only powerful weapons but also a secret that could change the balance of power in the Origin System. Also, a plot about a Tenno's struggle to control a newly acquired and extremely powerful Warframe that has a mind of its own could be really engaging.
Well, you could have a survivor fan fiction where a contestant has a hidden skill, like being able to communicate with animals on the island. This could give them an edge in finding food and avoiding danger. Or perhaps a story where there's a traitor within the group, someone who is secretly working with the show's producers to create more drama. Also, a plot where the survivors find a map that leads to a hidden part of the island with a bountiful supply of food and shelter.
One idea could be that the Ghostbusters discover a new type of ghost that can possess technology. So they have to find a way to stop it from taking over all the electronics in the city. It would be a race against time as the city starts to descend into chaos with machines going haywire.
One idea could be a story where a minor character from the game gets a chance to become a hero. For example, a low - level soldier who discovers a hidden power within himself and uses it to save his comrades during a crucial battle.
One interesting plot idea could be exploring what would happen if Aladdin's three wishes had unforeseen consequences that affected not just him but the whole city. For example, a wish for wealth might lead to an economic imbalance.