One idea could be that Eragon and Saphira travel back to a time when the Dragon Riders were first formed. They could witness the original pacts between dragons and riders, and perhaps even influence the early development of their order in a positive way, like sharing some of the knowledge they have from their own time.
Maybe they travel to a future time where the world has been completely changed by magic. They find that dragons are no longer feared but revered as gods. Eragon and Saphira then have to figure out how to get back to their own time while also dealing with the new power dynamics and cultures they encounter.
Well, a great plot for Eragon and Saphira fanfiction could be a story centered around Saphira learning a new and extremely powerful form of magic that she can't fully control at first. This causes all sorts of chaos and Eragon has to help her master it. Or perhaps a fanfic where Eragon and Saphira encounter a group of rogue dragons who have a very different view on how dragons and riders should interact. They then have to decide whether to fight them or try to persuade them to their side. Also, a story where Eragon and Saphira are magically shrunk to a very small size and have to survive in a world that is now giant compared to them could be really interesting.
Galbatorix could still be a main antagonist even in a time - travel scenario. If they travel back in time, he could be younger and more powerful in different ways. Maybe they accidentally give him knowledge that makes him even more of a threat earlier in history.
There could be a fanfiction where Eragon and Saphira have to protect a small village from a group of dark mages. This would show their loyalty to the people and their strength as a team. The story might include how Eragon uses his magic in new and creative ways, guided by Saphira's wisdom, to outwit the mages and keep the village safe.
There are fanfictions where Eragon and Saphira have human forms and interact with normal humans in a medieval - like setting. In these stories, they might experience human emotions more deeply, like love and friendship in a different way. For example, Eragon in human form could fall in love with a human girl, and Saphira has to help him navigate this new relationship while still maintaining their dragon - rider bond.
In this type of fanfiction, the 'lemon' aspect might add a layer of emotional and physical closeness that could be used to show a different side of their relationship. However, it's important to note that not all fanfictions with this tag will focus solely on that. Some may use it sparingly to enhance the overall relationship development. For example, it could be used to show a moment of extreme trust and vulnerability between the two characters.
Arya could be a great addition. She has her own set of skills and knowledge that could add depth to the story. Murtagh is also an interesting character. His complex relationship with Eragon and his own journey could bring in a lot of drama. Nasuada, with her leadership skills and strategic mind, could play a crucial role in any fanfiction scenario. For example, in a story where there is a war, Nasuada could be leading the troops while Eragon and Saphira are dealing with a magical threat.
One idea could be that Merlin, with his magic from the Arthurian world, meets Eragon in Alagaesia. Maybe Merlin helps Eragon to better understand and control his own magic, as Merlin has centuries of experience. He could teach Eragon about different forms of magic and how to use it more subtly.
One idea could be an OC who is a healer in Alagaësia and gets caught in the middle of the conflict between Eragon and Murtagh. They could try to use their skills to heal the wounds of both sides, physically and emotionally. Another could be an OC with a special power related to magic that neither Eragon nor Murtagh have seen before, and this power could either be a threat or an advantage in the ongoing battles. A third idea is an OC who is from a different part of Alagaësia and has a different cultural perspective on the whole dragon - rider situation. This OC could try to broker peace between Eragon and Murtagh, bringing in new ways of thinking about their roles and destinies.
One idea could be that Eragon discovers unique dragon magic only accessible to those raised by dragons. For example, he might be able to communicate with all dragons on a deeper level, not just his own. Another plot could involve him facing challenges from dragon - haters who fear his special bond with the dragons. They might try to break the bond or harm him.
Well, perhaps Eragon's dragon, Saphira, is injured and they have to seek out the healing magic in Skyrim. Along the way, they meet the Dragonborn. The two dragon - related characters could either become friends or rivals. Eragon might be amazed at the variety of dragons in Skyrim, some of which are different from the ones he knows. And he could share his knowledge of dragon - riding with the Dragonborn.