A third plot idea is a body - swap situation. Due to some magical mishap, Naraku and Kagome swap bodies. They are forced to live in each other's shoes for a while. Naraku, in Kagome's body, has to deal with her family and friends, and Kagome, in Naraku's body, has to face his minions and the other demons. This situation makes them understand each other better. As they try to find a way to reverse the spell, they start to see each other in a new light and develop feelings that were not there before.
Well, a plot could involve Naraku being cursed to feel all the pain he has caused, and Kagome is the only one who can ease his suffering. So he has to follow her around. Or perhaps in a fanfiction, Naraku and Kagome get trapped in a magical realm where they have to rely on each other to survive. Also, a story could be about Naraku having a split personality, and one part of him is attracted to Kagome and tries to break free from his evil self to be with her.
One plot idea could be that they have to save a village from a mysterious curse. Inuyasha uses his combat skills and Kagome uses her knowledge of the spiritual world to find a solution. Another idea is that they get separated in a strange new land and have to find their way back to each other while facing various obstacles alone.
The concept of change is a big theme. Naraku's character is usually set to change, either for the better or in a more complex way. Kagome also changes as she deals with Naraku. These changes are often the driving force of the plot. It's not about physical relationships but about the internal and external changes that occur within the two characters in relation to each other.
Another plot could be that Kagome gets lost in a dangerous part of the spirit world and Sesshomaru, who happens to be there, reluctantly decides to help her find her way back. As they journey through the spirit world, they encounter various challenges that force them to rely on each other. Kagome might use her spiritual powers in new ways, and Sesshomaru could show a more protective side.
A plotline could be that Naraku is cursed in a way that only Kagome can break the curse. This forces them to be in close proximity and work together. As they do, they start to understand each other better. Kagome realizes that Naraku's actions in the original series were partly due to the circumstances he was in, and Naraku starts to see Kagome's kindness as something more than just a weakness.
A possible plot could be that Naraku somehow manages to capture Kagome and tries to use her to gain more power. But in the process, there are some unexpected emotional developments between them. However, this is a very different take from the original Inuyasha story where their relationship is mainly one of enmity.
One plot idea could be a story where Kagome discovers a hidden message or prophecy left by Inutaisho. She then embarks on a journey to decipher it, which leads her to learn more about Inutaisho's past and his true intentions. Along the way, she meets various characters who knew Inutaisho and gains a deeper understanding of him.
One idea could be that Ash discovers a rare and powerful Pokemon that has been injured. He takes it upon himself to nurse it back to health. During this time, they form a deep bond based on trust and mutual respect. The Pokemon then decides to join Ash on his journey, and they face many challenges together, learning new moves and strategies along the way.
A plot could revolve around Orihime getting lost in Hueco Mundo and Grimmjow being the one to find her. Instead of harming her as he might have in the original story, he decides to help her find her way back. Along the way, they start to see each other in a new light and form a bond based on mutual respect and friendship. Or perhaps they both end up in a strange dimension where they have to rely on each other's skills to survive and escape, and this experience changes their relationship for the better.
A third plot idea is that the reader is a new inhabitant in the Underground and they accidentally stumble upon Mettaton's secret rehearsal space. Mettaton is initially angry but then realizes the reader has some unique ideas for his show. So they start working together to improve his act. This could involve the reader teaching Mettaton some new moves or concepts from the human world that he hadn't thought of before.