One idea could be exploring Midna's backstory in more detail. Maybe how she came to be in the Twilight Realm and her relationships there before meeting Link. Another could be a story where Link has to face a new, previously unknown enemy in the Twilight Realm that is even more powerful than Zant. For example, an ancient evil that was sealed away long ago but is now starting to break free.
One idea could be to create an OC who is a traveling merchant in the Twilight Realm. They could have unique items to sell that are related to the Twilight magic, like enchanted amulets that can temporarily give Link enhanced abilities in the Twilight. Another idea is an OC that is a member of a secret society in Hyrule that has been studying the Twilight for generations and has their own motives regarding its presence. Maybe they see Link as a key figure and try to either help or hinder him depending on their goals.
You could also focus on a side character from the game. Let's say the Poe Collector. Write a story about his adventures collecting Poes in different parts of Hyrule and how he might get involved in the larger events related to the Twilight Princess plot.
One idea could be Link and Ilia going on a secret adventure to discover a hidden magic within the Twilight Realm. Maybe they find an ancient artifact that has the power to restore a part of the Twilight Realm that was damaged. Another could be a story where Ilia gets kidnapped by an unknown enemy and Link has to go through a series of difficult trials to rescue her. He could face new and dangerous creatures along the way.
A great idea for a BotW fanfiction could be a 'what if' scenario. For example, what if Link failed to defeat Calamity Ganon? You could write about how Hyrule is plunged into even deeper despair, and how the remaining survivors, including Zelda, try to fight back. Or perhaps a story centered around the different races of Hyrule working together to build a new city, away from the ruins of the old Hyrule Castle. This could explore their relationships and how they combine their unique skills.
One common theme is friendship, especially the bond between Midna and Link. Many fanfictions explore how their relationship evolves and endures. Another theme is self - discovery. Midna's journey of understanding herself and her powers is often depicted. For example, in some fanfictions, she learns about her true origin and purpose. Power and responsibility is also a common theme. As Midna has certain powers, she has to deal with the consequences of using them, like in 'Midna's Hidden Powers' where she discovers new powers and has to figure out how to use them responsibly.
Some interesting concepts for 'the legend of zelda fanfic' include a story set in a future Hyrule where new technology has emerged but still coexists with the ancient magic. Or perhaps a fanfic where the villains from different Zelda games team up against Link and Zelda. You could also write a story centered around a young Link growing up in the Kokiri forest, his daily life, his friendships, and how he discovers his destiny in a more gradual and personal way.
Well, a cool Legend of Zelda fanfic idea might be to create a story where all the different Links from various timelines come together. They could team up to fight a new, super - powerful enemy that threatens all of their worlds. Or perhaps a fanfic that takes place in a parallel Hyrule, one with different rules and cultures. For example, a Hyrule where magic is outlawed and the characters have to find other ways to survive and thrive. Also, a fanfic about the origin of the Triforce, told from the perspective of the ancient sages who first discovered it.
Some non - adult themes include the role of the spirits in the Twilight Realm. How they guide Link or influence the events in the game world can be a fascinating topic. The restoration of the balance between light and dark is also a great theme. Fanfiction can show how Link, through his actions, tries to bring back harmony to the land. And the relationships between the various characters in the game, not in a romantic or sexual way, but in terms of loyalty, trust, and camaraderie, are also interesting themes to explore.
One idea could be that Link, the hero from Legend of Zelda, somehow gets transported to the world of MLP. He might team up with Twilight Sparkle to fight against a common enemy that threatens both their worlds. Maybe Ganon has found a way to corrupt the magic in Equestria, and Link's combat skills along with Twilight's magic knowledge are needed to stop him.
One idea could be exploring Link's life before he woke up in the Shrine of Resurrection. Maybe he had a family or a best friend in a small village that was lost during the Calamity. Another idea is to focus on Zelda and her struggles with her powers in a more in - depth way, like her inner thoughts and fears during her time trying to unlock her sealing power.