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 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.
A really interesting crossover is when Naruto's chakra abilities are combined with the Men in Black's high - tech gadgets. For example, in some fanfics, Naruto uses his shadow clone jutsu to create clones that can operate the Men in Black's advanced weaponry, which creates a really unique and exciting scenario.
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.
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 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.
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 crossover could be Naruto characters having to adapt to the modern warfare setting of Black Ops 2. For example, Naruto's speed and agility might make him an excellent infiltrator. He could use his Shadow Clone Jutsu to create diversions during missions. Sasuke, with his Sharingan, could be a great sniper, able to analyze the battlefield and enemy movements quickly. Another aspect could be the use of ninjutsu in the context of the game's maps. For instance, using Earth - Style jutsu to create barriers or tunnels in the urban maps of Black Ops 2.
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.
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.