First, think about her unique weapon form. Maybe it could be something like a celestial harp that can also transform into a scythe. Then, give her a distinct personality. For example, she could be shy but fierce in battle. Also, consider her backstory, like she comes from a long line of musicians but chose to be a weapon meister instead.
Good plot ideas include your female OC trying to break a curse that has been placed on her weapon form. She might have to seek out a reclusive and powerful character for help. Also, a plot where she is framed for a crime she didn't commit in the Soul Eater academy and has to clear her name while also dealing with the real culprit who is still at large.
One idea could be to create an OC weapon that is a scythe with a hidden blade. It could have a unique backstory, like it was forged in a forgotten realm. The character using it could be a bit of a rebel, not fully conforming to the rules of the Death Weapon Meister Academy.
One common theme is the struggle of the OC to fit in. In a world filled with unique and powerful characters like in Soul Eater, the OC often has to prove themselves worthy. And of course, the harem aspect usually involves different types of relationships - from friendship to romantic interests.
Another theme is friendship and rivalry. The male OCs usually interact with the existing Soul Eater characters. They form strong friendships with some, like Maka and Soul, while having rivalries with others. This creates interesting dynamics and storylines. For instance, a male OC might compete with Black Star for the title of the best fighter.
In many Soul Eater fanfictions involving Blair and an OC (Original Character), the relationship can be quite diverse. It could be a friendship where the OC helps Blair in her various adventures in the Soul Eater world. Maybe the OC has some special abilities that complement Blair's magic. For example, if the OC is good at tracking souls, they could assist Blair in finding more powerful souls to consume.
A believable OC in Soul Eater x OC fanfiction can be created in multiple ways. Begin with their motivation. What do they want to achieve in the Soul Eater world? Is it to become a great meister - weapon pair? Or is it to uncover some long - lost secret? Their motivation will be the driving force behind their actions. Next, consider their flaws. No one is perfect, and neither should your OC be. Maybe they are too impulsive or overly cautious. Their flaws make them more human. Also, think about how they interact with the existing characters in the series. Do they get along with Soul and Maka? Or are they more likely to clash with Black☆Star? By carefully crafting these aspects, you can create an OC that feels like they belong in the Soul Eater universe.
Create a multi - layered plot. Maybe there's a mystery surrounding the origin of the OC weapon. As the fanfiction progresses, the characters start to uncover clues about its creation and purpose. At the same time, there could be a romantic sub - plot between the meister and another character at the academy. This adds depth to the story and keeps readers interested. Also, don't forget to have a climax where the characters face their biggest challenge yet and a satisfying resolution at the end.
One common plotline is the OC being a new student at the DWMA (Death Weapon Meister Academy). Blair then takes an interest in this new and unique character. They might start off as strangers, but as the story progresses, they form a bond. For instance, the OC could be targeted by an evil force, and Blair decides to protect them.
Maybe an OC that has a special ability related to time. They can slow down time briefly during a fight. But this power comes with a cost, like it drains their soul energy quickly. The fanfiction could explore how they learn to control this power and balance its use while also dealing with the normal challenges at the DWMA, such as making friends and passing classes.