A great concept could be the Brotherhood of Steel having to team up with their former enemies in a crossover fanfic. This would lead to some really interesting character development as they have to put aside their differences and work towards a common goal. There could be a lot of internal conflict within the Brotherhood as some members struggle with this new alliance, while others see it as a necessary evil to survive in a more dangerous world.
One interesting concept could be the introduction of characters from different universes into the Brotherhood of Steel's world. For example, bringing in a character with unique powers or a different moral code and seeing how they interact with the strict, technology - focused Brotherhood.
One interesting concept could be new jutsu combinations created by the characters. For example, the main characters might develop a jutsu that combines fire and wind elements in a unique way that wasn't seen in the original Naruto series.
Paladin Danse is often a popular character. His loyalty to the Brotherhood and his complex backstory make him a great focal point in crossovers. Writers can explore his reactions to new characters or situations from other universes.
One interesting concept could be the unique abilities associated with Steel Release. Maybe the characters can create and manipulate steel in ways that are different from other chakra - based techniques. For example, they could form impenetrable steel shields or sharp steel projectiles.
Another concept is the Joker's influence on the story's tone. In a crossover with a more light - hearted or comical universe, the Joker could still bring his dark and menacing presence, which would create a really interesting contrast. His actions and words could disrupt the normalcy of that universe and force the other characters to deal with a level of chaos they're not used to.
Another concept could be a time - travel - based crossover. Suppose Doraemon crosses over with Doctor Who. They could both explore different time periods and dimensions together. Doraemon's Time Machine and Doctor Who's TARDIS are both means of time travel, but they have different functions and appearances. Their combined adventures would be full of mystery and discovery.
One interesting concept is character interactions. For example, seeing how characters from different timelines or universes react when they meet. Another is the alteration of established storylines. It can create unique plot twists.
One interesting concept could be a 'Warhammer' crossover with 'Lord of the Rings'. Imagine the orcs from 'Warhammer' interacting with the orcs from Middle - earth. Another could be a crossover with 'Star Wars', like the Space Marines teaming up with the Jedi or Sith in some strange alternate universe scenario. And a 'Warhammer' and 'Harry Potter' crossover where the magic of the wizarding world meets the dark and gritty world of 'Warhammer' would also be really cool.
One interesting concept could be a Godzilla crossover with other giant monster franchises like King Kong. It could lead to epic battles and new storylines where they have to team up or fight over territory. Another concept might be a crossover with a superhero universe. Imagine Godzilla facing off against the Avengers or Justice League, which would require different strategies from both sides.
One interesting concept could be a xenomorph crossover with a superhero universe. Imagine a xenomorph invading a city where superheroes exist. The heroes would have to use their unique powers to fight this alien threat. For example, a telekinetic hero could try to hold the xenomorph in place while others figure out a way to kill it.
One interesting concept could be the interaction between Ultron and characters from different universes. For example, how Ultron would react to superheroes with completely different powers and moral compasses.