Naruto himself could be a great crossover character. Since Kakashi is his mentor in the original series, seeing them interact when Kakashi is a kid could be really interesting. They could have a different kind of dynamic, with Naruto perhaps being the more experienced one in some aspects. Another potential character is Goku from Dragon Ball. The contrast between Kakashi's ninja skills and Goku's martial arts and superpowers would create a really exciting crossover.
One common theme is power adaptation. Since Kakashi is from the ANBU, he has a certain set of skills. In crossovers, he has to adjust these skills to fit the new world he's in. For example, if he crosses into a world with magic, he might need to figure out how his ninja techniques work with the new magic system.
One common theme is the clash of cultures. Kakashi comes from the ninja world of Naruto, and when he enters the Bleach universe, there's a contrast between the two. For example, the way they handle combat and the hierarchies in their respective worlds.
One idea could be that Kakashi is somehow transported to the My Hero Academia world. He could become a teacher at UA, using his ninja skills and wisdom to train the students in new and unique ways. His Sharingan would be a very interesting power in the MHA universe.
One popular Kakashi crossover fanfiction could be a crossover with the Naruto and Harry Potter universes. In such a story, Kakashi might find himself at Hogwarts, with his unique ninja skills and Sharingan causing quite a stir among the wizards. He could potentially teach the students some new forms of combat or be involved in a battle against dark wizards.
In a Naruto Kakashi crossover fanfiction, to develop Kakashi's character, you could introduce a new love interest for him from the crossover world. This would make him open up more emotionally and show a different side of him. As for Naruto, put him in a situation where he has to teach Kakashi something. Maybe in a world where Naruto's positive attitude is the key to solving a problem that Kakashi can't figure out. This would not only show Naruto's growth but also make their relationship more equal, and both characters would be developed in new and interesting ways.
Another theme is often friendship and cooperation. Since Kakashi and the characters from Harry Potter come from different worlds but have to work together in these crossovers. They learn from each other's strengths and overcome their differences. For example, Kakashi can teach the wizards about stealth and physical combat skills, while the wizards can show Kakashi new magical abilities. It's about building bonds across different universes.
One idea could be a crossover with the Harry Potter universe. Kakashi could be a visiting wizard from another dimension, teaching the students at Hogwarts some of his ninja skills. Another could be a crossover with the Avengers. Kakashi's stealth and combat skills would make him a great addition to the team, and it would be interesting to see how he interacts with the likes of Iron Man and Captain America. A third idea might be a crossover with the Lord of the Rings. Kakashi could be a ranger in Middle - earth, using his Sharingan to detect the presence of orcs and other dark forces.
In Dark Kakashi fanfiction, a pairing that has gained popularity is Kakashi with characters from the 'Hellsing' universe. The dark and violent nature of both Kakashi's darker side and the Hellsing world can create some intense and action - packed stories. Additionally, Kakashi crossovers with characters from the 'Tokyo Ghoul' series are also quite common. His own inner demons can be paralleled with the struggle of the ghouls in that world.
Well, for Dark Kakashi crossover fanfiction, Tumblr can be a useful resource. There are many fanfic writers and fans who post about their works or share links to great stories there. Also, some Naruto - focused forums might have sections dedicated to fanfiction. These often have users discussing and recommending different fanfics, including those with Dark Kakashi in crossovers. Just be sure to explore different threads carefully.