The character interactions are a big draw. Picture Naruto meeting Death the Kid. Naruto's brash and determined personality contrasts with Kid's more precise and somewhat OCD nature. They could learn from each other or get into comical misunderstandings. Also, Sakura and Maka could have some interesting girl - power moments together, comparing their combat skills and medical knowledge (in Sakura's case).
The exploration of new worlds. Fanfics often take Naruto to the Soul Eater world or vice versa. This allows for a whole new setting to be explored. In the Soul Eater world, Naruto would encounter things like the DWMA (Death Weapon Meister Academy). He'd have to adapt to the school system there, make new friends and enemies, and figure out how to survive in a world where the main goal is to keep the balance of souls. It's a great opportunity for creative and exciting storylines.
One unique aspect is the combination of power systems. Naruto has his chakra and jutsu, while Soul Eater has the concept of souls and weapons. In fanfiction, seeing how these different power elements interact is really fascinating. For example, a story might show Naruto using his Rasengan with a Soul Eater - style weapon.
The character interactions are also very appealing. Imagining Natsu from Fairy Tail teaming up with Maka from Soul Eater is quite fascinating. They have different personalities but similar goals in a way, like protecting their friends and their respective worlds. It's interesting to see how they would communicate and work together.
Some fanfictions of this kind might focus on the relationships that are affected by Black Star. For instance, his relationship with Maka and Soul. Without his constant interference or competition, Maka and Soul might have a different kind of friendship or partnership. Additionally, it could be used to create more complex villains. Since Black Star is often in the front line fighting, without him, the villains could be portrayed as more menacing and strategic as they don't have to deal with his brash attacks. This type of fanfiction gives a chance to rewrite parts of the Soul Eater story in a new and unexpected way.
One interesting crossover could be Naruto's ninjutsu skills combined with Tsubaki's weapon forms in the Soul Eater world. For example, Naruto could use his Rasengan while Tsubaki is in her sword form to create a super - powered attack. Another idea is the characters from Naruto learning about the concept of souls in the Soul Eater universe and how they could use their own chakra to interact with souls.
The power dynamics are often very interesting. Voldemort is such a dominant figure, and seeing how the Death Eaters interact with him, whether out of fear or true loyalty, makes for a great read. For example, in some fanfictions, a Death Eater might try to gain more power within Voldemort's ranks, which leads to all sorts of tense situations.
One plot idea could be Patty somehow getting transported to the Naruto world and using her Soul Eater abilities to fight alongside the ninjas. For example, her weapon skills could be a great asset in battles against the Akatsuki.
A common interesting plot point is the clash of the two different educational systems. Hogwarts' classes and the DWMA's training are very different, and seeing how characters adapt to this is cool.
The idea of a common enemy is also very appealing. Maybe a powerful demon from Inuyasha's world that is so strong it threatens both worlds, and the characters from both series have to work together. This forces them to overcome their initial misunderstandings and differences. For instance, the Soul Eater crew might not trust Inuyasha at first because of his demon side, but as they face this huge threat, they learn to rely on each other.
The creativity in plot is also a great part. Fanfics often take the basic concepts from the original source, like Soul Eater, and twist them in new ways. In a soma - related fanfic, perhaps there are new challenges for Soma that are different from what we see in the official story. This could involve his relationships with other characters, or his journey to master certain abilities in a different context.
One idea could be a crossover where the Juubi's power somehow gets transferred to a character in Soul Eater and they have to learn to control it. Another could be Naruto getting lost in the Soul Eater world and having to adapt to their way of fighting and dealing with souls.