Juvia might also be a good candidate. She's deeply in love with Gray already, so the concept of her becoming the end bride could add a whole new layer of drama. Her water magic could be used in unique ways in the context of the end bride story, like creating a magical shield around herself and her loved ones as she steps into the role of the end bride.
Well, a plot idea could involve the end bride being a long - lost princess of a magical kingdom. The Fairy Tail members discover this and have to protect her from those who want to use her for their own gain. As she gets closer to becoming the end bride, she discovers her true powers and uses them to save the guild. Also, perhaps she's an amnesiac and as she falls in love with a Fairy Tail member, her memories start to return and they are related to her role as the end bride.
In my opinion, Makarov could be the ideal Fairy Tail guild master in game fanfiction. He has great leadership skills and a strong sense of justice. His magic power is also quite formidable, which can add a lot of exciting elements to the game.
Lucy could also be the main character. Since she has celestial spirit magic, she could use her connection with the spirits to learn more about the Book of End. Maybe one of her spirits has some knowledge about it. Also, as a smart and determined character, she could lead the investigation into the mysteries of the book and face any threats that come her way.
To end a Fairy Tail fanfiction, it could be interesting to look at the future. After the main events of the story are over, write a short epilogue that shows where the characters are headed. Are they going on new adventures? Have they retired from the guild? You can also end it on a bittersweet note. For instance, a character may have to leave the guild to pursue a personal dream, but they leave with the love and support of their friends, showing that change can be both sad and positive.
One popular 'End Join Fairy Tail' fanfiction might be 'The New Adventure'. It often features new characters joining the Fairy Tail guild and going on unique quests. Another could be 'End Join: The Power Within' which focuses on the development of the joined characters' powers within the Fairy Tail universe.
Sure, in the 'Fairy Tail' universe, the concept of Natsu being END is quite fascinating. Fanfiction writers often take this idea and run with it. They might create stories where Natsu discovers his true nature as END more gradually, or they could write about how the other guild members react when they find out. It can also lead to stories that explore the origin of Natsu as END and how it ties into the overall lore of the 'Fairy Tail' world.
One way it could end is with a big showdown. The Fairy Tail guild members find the kidnappers' lair, and there's an epic battle. Natsu defeats the main kidnapper with his powerful fire magic, and Lucy is freed. Then they all return to the guild, where there's a big celebration.
Storm Fullbuster, son of Gray and Juvia. He could have a unique blend of ice and water magic. His story could revolve around him trying to live up to his parents' legacies while also forging his own path in the guild.
Erza could also be a possibility in some fanfictions. She is strong and independent, and Natsu respects her a great deal. A relationship between them would be full of interesting dynamics, like how they would handle their different leadership styles when they are together, and how their relationship would affect the guild as a whole.
It could be a rival guild. There are other guilds in the Fairy Tail universe that might be jealous of Fairy Tail's power and reputation. They could kidnap Mirajane to try and weaken Fairy Tail. For example, Phantom Lord has had conflicts with Fairy Tail in the past.