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.
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 theme is self - discovery. Since the OC weapons are often new creations in the fanfic world, they usually have to figure out their powers, which is like a journey of self - discovery. For example, they might find out they can transform in unexpected ways or have special abilities they didn't know about.
One great Soul Eater Weapon OC fanfic is 'The New Weapon in Death City'. It has an interesting plot where the original character is a weapon with a unique transformation ability. The story focuses on how this OC weapon interacts with the main characters from the Soul Eater universe, bringing new challenges and friendships.
Naruto might be a staff - type weapon. He could use it for both close - range combat and to channel his chakra or soul power. The staff could have different forms, like it could extend or transform into other shapes depending on the situation, similar to how he can transform his Rasengan.
In a fanfiction where Black Star becomes a weapon, his design as a weapon would probably be very unique. Given his love for being flashy and his ninja - like style, he could be a weapon that has a lot of sharp edges and a sleek, black design. Maybe he'd be a sword with some sort of special ability related to his ninja skills, like being able to disappear and reappear during combat, or having the ability to cut through dimensions.
Well, perhaps Harry could be a weapon that has the power of his magic from the Potter world. He might be used by a Soul Eater character to fight against evil souls. Maybe his wand could transform into a more weapon - like form in the Soul Eater world.
It's rather unique. Combining the magical world of Harry Potter with the concept of Weapon Soul Eater is not something you see every day. Usually, fanfictions tend to stay within the same universe or have more common crossovers. This one seems to blend two very different and popular franchises in a new way.
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.