Friendship is a very common theme. Sting and Rogue are often depicted as having a deep and unbreakable friendship. Another theme is adventure. They go on various adventures together in many fanfictions. And of course, the theme of magic is always there as they are part of the Fairy Tail world which is full of magic.
Another common theme is power and growth. Writers often show how Rogue and Sting become stronger over time. For example, they might face a powerful enemy and through that experience, they learn new magic or improve their existing skills. It's about their journey to become more powerful dragonslayers.
One common theme is friendship. Since they are both dragon slayers in Fairy Tail, their friendship is often explored, like how they support each other through tough times.
The theme of loyalty also pops up a lot. Their loyalty to each other, to their guild, and to their ideals is a key part. It's often tested in various situations, like when they are faced with a choice between their own desires and the greater good of the guild or their friends.
Well, a really popular theme is power - up. In these fanfictions, Sting and Lucy often find ways to increase their magical powers while working together. It could be through a special training or finding a rare magical item. Another common theme is the exploration of their pasts. How their individual histories shape their relationship is an interesting aspect that many fanfiction writers like to touch on. Also, the theme of loyalty comes up a lot, especially when they face difficult situations and have to choose whether to stay true to each other or not.
A significant theme is redemption. Sting was initially an antagonist - like character. Fanfic writers often delve into how he redeems himself in the eyes of the other characters and the guild. There are also themes related to power struggles. As Sting is a powerful mage, fanfictions may explore how he deals with others who are either jealous of his power or try to use him for their own gains.
One common theme is the exploration of their powers together. Since they both have strong magical abilities in the Fairy Tail universe, fanfictions often show them training or using their powers in unison against enemies.
One idea could be a story where Sting and Rogue have to go on a special mission together in a new, uncharted land. They face various magical creatures and have to learn to trust each other even more. Another could be a fanfic set in an alternate universe where they are not part of Fairy Tail, but are instead traveling rogues who cross paths with characters from Fairy Tail in unexpected ways.
For Lucy, you could develop her character by showing her growing more confident in her magic. Maybe she starts to experiment with new ways to summon her Celestial Spirits or combines their powers in unique ways. With Sting, you can explore his past more deeply. Show how his experiences as a Dragon Slayer have shaped his personality, and have him face some internal conflicts related to his power and identity. As for Rogue, you could develop his relationship with his shadow. Maybe he discovers new abilities within his shadow magic. Also, in the fanfiction, put them all in situations that force them to interact and grow together. For example, a mission where they have to protect a village from a powerful dark mage.
A possible plot could involve a dark magic that starts affecting Fiore. Lucy discovers some ancient texts about it, and she realizes she needs the help of Sting and Rogue. They go on a journey to find the source of this dark magic. Along the way, they encounter many enemies. Sting and Rogue use their Dragon Slayer magic to fight, while Lucy summons her Celestial Spirits. As they get closer to the source, they find out that one of their old enemies has returned and is using this dark magic to seek revenge. Together, they combine their powers to defeat the enemy and save Fiore.
One great fanfiction could be 'The Bond of Dragonslayers'. It really delves into the relationship between Rogue and Sting. It shows their growth as characters, their teamwork, and how they support each other. It also has some really cool action scenes that are true to the Fairy Tail spirit.