The planetary anchor could be a device created by an ancient civilization in the Fairy Tail universe. It was lost over time, but now it resurfaces. It has the ability to control the tides of magic across different planets. In the fanfiction, the Fairy Tail mages must race against other guilds or dark forces to obtain the anchor and use it to prevent a magic imbalance that could destroy their world.
One idea could be that the planetary anchor is a powerful ancient relic that gets discovered in the Fairy Tail world. It has the power to stabilize the magic energy of the planet, but an evil force wants to use it to drain all the magic. The Fairy Tail guild has to protect it and figure out how to use it for good.
I'm not sure specifically as it could cover a wide range of things. It might be a fan - made story in the 'Fairy Tail' universe that involves some sort of planetary anchor concept. Maybe it's about a magical item or power that acts as an anchor for a planet in the 'Fairy Tail' world.
One possible plot idea could be that the planetary anchor is a powerful magical artifact in the Fairy Tail universe. It could be the key to unlocking a hidden dimension filled with ancient magic. The characters might embark on a quest to find all the pieces of the anchor and face various challenges along the way, including battles with dark mages who also want to use the anchor's power for evil.
You could try fanfiction websites like FanFiction.net or Archive of Our Own. They have a large collection of 'Fairy Tail' fanfictions and there's a good chance you'll find the 'fairy tail planetary anchor' one there.
It could be incorporated as a McGuffin. For example, the characters hear rumors about the planetary anchor and its great power. They then go on a quest to find it. Along the way, they encounter various challenges and enemies related to those who also seek the anchor.
Another great plot for this fanfiction could be that a powerful dark force from Skyrim threatens the Fairy Tail world. The Fairy Tail wizards, being used to their own types of threats, are initially confused by this new and different kind of evil. But with the help of some Skyrim characters like the Companions, they learn to adapt and fight back. This would involve a lot of character development as they learn from each other's strengths and weaknesses.
One idea could be that the Fairy Tail mages are transported back to the Stone Age. They have to use their magic in new ways to survive, like using fire magic to keep warm and cook food. Maybe they encounter prehistoric creatures and have to figure out how to deal with them without modern technology.
One idea could be that Aries discovers a new type of celestial magic that she has to keep secret from the other celestial spirits. She struggles with whether to tell Lucy or not, as it could put her in danger. Another plot could involve Aries getting lost in a different dimension while on a mission with Lucy and having to find her way back, all the while learning more about her own powers and past.
One idea could be to insert yourself as a new member of Fairy Tail guild. You could have a unique magic ability, like the power to control elements in a different way than the existing characters. For example, instead of just summoning fire, you can manipulate its shape and intensity in a more creative way.
One idea could be to focus on a new character in the Fairy Tail world with a unique color - related magic. For example, a character who can manipulate colors to create illusions or even use them as a form of defense. They could join the Fairy Tail guild and have all sorts of adventures with the existing members.
A great plot idea for Fairy Tail fanfiction could be that a mysterious force starts stealing the magic of all the mages in Fiore. The Fairy Tail guild has to team up with other guilds, including their rivals, to find out who or what is behind it. Also, you could have a plot where one of the main characters loses their magic completely and has to find a new way to be part of the guild and fight. Maybe they discover a hidden form of non - magical combat that still uses the spirit of Fairy Tail. Another plot could be that an otherworldly being comes to Fiore and challenges the strongest mages, including those from Fairy Tail, to a tournament to decide the fate of the world.