One idea could be that the princess has a secret power that is awakened by the Twilight world. Maybe she can communicate with the Twilight creatures and they help her solve a mystery in her own kingdom.
Another plot could be that the Twilight world is in danger and the princess, with her unique human qualities, is the key to saving it. The Twilight characters initially don't trust her, but as she shows her courage and kindness, they come to rely on her.
A great plot for a Twilight Princess story fanfiction could be a time - travel aspect. Link somehow gets sent back in time to a point before the Twilight invasion. He could then try to prevent it from happening in the first place. This would involve him interacting with characters in a different way, and he might have to make some tough decisions about changing the future.
A fanfiction could explore the backstory of some of the side characters in both games. For instance, in Twilight Princess, you could write about the life of Midna before she got involved with Link. Or in Skyward Sword, you could delve into the past of Groose and how his relationship with Link developed over time. This could add more depth to the overall Zelda universe in the fanfiction.
One interesting plot idea could be exploring how different characters adapt to the post - apocalyptic world in new and unexpected ways. For example, a character who was once a timid office worker becomes a fearless scavenger.
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 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 plot could involve a new vampire in the Twilight universe who is ashamed of their transformation and uses a mask to try and fit into human society again. They struggle with their new instincts while trying to keep their identity a secret. Along the way, they meet other characters from the Twilight series and their story unfolds in a way that challenges the norms of the original story.
One idea could be a new vampire character being reborn in the Twilight universe with a special power, like the ability to control the weather. This would create a whole new dynamic as they interact with the Cullens and other vampires.
One idea could be exploring a new magical creature in the Twilight universe. For example, a magical being that can control time and how it affects the relationships between vampires, werewolves and humans. Another plot could involve a character from the Twilight world getting lost in a different magical realm and having to find their way back, all while facing new and strange challenges.
One plot idea could be a hockey player who discovers he has a special power during a twilight game, like being able to skate at super - speed. Another could be a love story between a hockey fan and a player, set against the backdrop of twilight - filled evenings at the rink. Maybe a story about a hockey team's struggle during the twilight of their careers, with an old - timer coming out of retirement to save the day.
One idea could be exploring the origin of the psychic powers in the twilight world. Maybe there was an ancient event that triggered it.