One common theme is redemption. Given Minerva's actions in the original series, many fanfictions explore her journey towards redemption, making amends for her past wrongdoings. For example, she might start to help the Fairy Tail guild in some way to atone.
Another theme is romance. She could be paired with different characters from the Fairy Tail universe. It might be a relationship with a Fairy Tail member, like Natsu or Gray, and the fanfiction could explore how their different personalities interact and develop feelings for each other.
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 popular theme is power - up. Writers often have characters from different universes learn new abilities from each other. For example, Naruto teaching Fairy Tail members about chakra control and in return learning new magic spells. Another theme is friendship. The idea of characters from Naruto and Fairy Tail coming together and forming strong bonds, with Minerva being a part of that group and how their different backgrounds influence their friendship.
One interesting Minerva Fairy Tail fanfiction could be about her backstory. Maybe it explores how she became the strong and complex character we see in the original. For example, a story could detail her early days in a dark guild and her journey towards redemption or a different path in life.
A third storyline could be about Rogue and Minerva getting lost in a mysterious and dangerous magical realm. They have to rely on each other's skills to survive. Minerva's powerful magic and Rogue's stealth abilities would be put to the test. As they explore this new realm, they encounter strange creatures and ancient magic that they must figure out how to deal with, all while growing closer as comrades.
Another theme is his relationships within the guild. He's a part of a community, so fanfictions often explore his friendships, rivalries, and how he interacts with other members. For example, how he might bond with Natsu over their love for a good fight or his more serious conversations with Erza.
Well, love is a typical theme too. Reincarnated characters may find love in their new existences, sometimes with someone they knew in a different way in their past lives. Power growth is also common. They start anew, but gradually regain or even surpass their previous powers. And of course, the theme of destiny plays a role. Their reincarnation might be part of a grand plan, and they are fated to achieve certain things in this new life.
One common theme is her relationship with Alzack. Many fanfictions explore their love story in more depth, like how they met or overcame challenges in their relationship.
There are also fanfictions that center around Gildarts' family. Since his relationship with Cana is an important part of the Fairy Tail story, some works explore more about their family ties, like how he became aware of Cana as his daughter and how they build a relationship. Additionally, his role in major Fairy Tail events from a different perspective can be a theme in these fanfictions.
One common theme is family. Since Grandine is a dragon in Fairy Tail, many fanfictions explore her relationship with her dragon - slayer child. They might delve into how she protects or guides her offspring from afar.
One common theme is the exploration of the relationship between the characters associated with Pisces in the Fairy Tail universe. For example, how they interact with other guild members.