One interesting crossover could be a scenario where characters from Naruto enter the world of Darker than Black. For example, Naruto's ability to never give up and his positive attitude might contrast with the often dark and morally ambiguous world of Darker than Black. He could potentially influence some of the Contractors there to question their own motives and actions.
Another interesting aspect could be delving into the backstories of minor characters but in a much darker light. For instance, what if Rock Lee had a past filled with abuse and trauma that made his drive to succeed even more complex? In this 'Naruto darker than black' fanfiction, we could see how these darker backstories shape the characters' present actions.
One plot idea could be that Naruto characters gain the powers of Contractors from Darker than Black. For example, Naruto himself could have a Contractor power related to his shadow clones, like being able to send his clones to different dimensions for a short time. Another idea is a story where the organizations in both universes collide. The Akatsuki from Naruto and the Syndicate from Darker than Black might have different goals but similar methods of achieving them. They could either fight or try to make an alliance depending on the situation.
One interesting story could be about a new Contractor with a unique power that changes the power balance in the Darker than Black world. Maybe they have the ability to manipulate time on a small scale, which leads to all sorts of adventures and conflicts with other Contractors.
A great crossover would be in a world where both Naruto and Black Adam exist. Black Adam could be intrigued by Naruto's ability to summon giant toads. He might see it as a form of magic similar to his own powers. Meanwhile, Naruto could be challenged by Black Adam's physical strength and have to rely on his ninja skills and strategic thinking to keep up. This could lead to a series of adventures where they learn from each other.
One interesting crossover could be a battle scenario. Naruto's powerful jutsu against Black Bolt's unique sonic powers would be epic. Maybe Naruto tries to use his shadow clone jutsu to overwhelm Black Bolt while Black Bolt uses his voice to take out the clones.
One interesting crossover could be a battle scenario where Goku Black's power and Naruto's ninjutsu clash. For example, Goku Black's hakai energy against Naruto's Rasengan. Another could be a story where they team up to fight a common enemy, perhaps an even more powerful villain from another dimension.
The mystery surrounding November 11 in Darker than Black provides a rich ground for fanfiction. It has an air of enigma that writers can explore further, like what really happened on that day, what secrets are hidden, etc.
One idea could be exploring Hei's past in more detail. Maybe a story where he has to face a threat from his old organization that forces him to remember things he'd rather forget. Another could be a fanfiction where Hei teams up with an unexpected ally, like a character from a different anime universe, to solve a mystery in the Darker than Black world.
Sometimes, you can also find them on specialized anime fanfiction forums. These forums might not have as large a collection as the big websites, but they often have some unique and high - quality fanfictions written by die - hard fans of the series. You might need to register on some of these forums to access the fanfictions though.
One interesting crossover could be Naruto ending up in the Black Butler universe and having to deal with the complex social hierarchy and supernatural elements there. He might use his ninja skills to fight off demons or other threats that Sebastian and Ciel face. Another could be Sebastian being intrigued by Naruto's chakra and trying to figure out how to use it for his own purposes in serving Ciel.