You could write a fanfiction about the relationships between the mutants that were not fully explored in the movie. For instance, how did the young mutants really feel about the older ones leading them into battle? Were there any unspoken rivalries or crushes among them? By delving into these aspects, you can create a more character - driven story that gives a fresh perspective on the 'X - Men The Last Stand' world.
A cool fanfiction concept could be a time - travel story within the 'X - Men The Last Stand' universe. Maybe a mutant discovers the ability to travel back in time and tries to prevent the events that led to the big battle. They could try to change the minds of key characters like Magneto or Jean Grey, which would completely change the course of the story. This would add a whole new layer of complexity and drama to the existing plot.
One idea could be exploring the backstories of the minor characters in more depth. For example, what was the life of that one mutant who had a brief appearance in the movie like before they came to Xavier's school? Another could be a different ending where the mutants find a more peaceful co - existence solution instead of the chaos in the actual movie.
The plot involves the struggle between mutants and humans reaching a critical point. There are battles over the 'cure' for mutation. Some mutants see it as a threat to their kind while others welcome it. Magneto, as always, is on the side of mutants' freedom and is ready to fight against those who would enforce the cure. The X - Men are divided in their views as well, with some trying to find a middle ground.
Perhaps Naruto is sent to the X - Men's world through some kind of interdimensional rift. He then has to adapt to their way of life while also showing them his ninja skills. The X - Men could be intrigued by his ability to use chakra to enhance his physical abilities and his various jutsu. They might even try to learn from him, and in return, Naruto could learn about mutant powers and how they use them for good in their world.
Another idea might be a story where a powerful mutant turns against the X - Men in the context of 'Termination'. This could create a lot of internal conflict within the group as they try to deal with this betrayal while also facing external threats. Maybe the mutant has a different view on how mutants should co - exist with humans and decides the X - Men are getting in the way.
One idea could be exploring the backstories of the minor mutants more. For example, how did they discover their powers before the events of Apocalypse. Another could be a time - travel fanfic where a mutant goes back in time to stop Apocalypse from ever rising to power. Maybe also a fanfic about the mutants trying to adapt to a post - Apocalypse world and rebuilding society in a more mutant - friendly way.
One idea could be creating an OC with a unique mutation that has never been seen before in the X - Men universe. For example, the ability to manipulate time on a small scale, like slowing down or speeding up time in a limited area. This OC could be a new student at the Xavier Institute and face challenges in controlling their power while also trying to fit in with the other mutants.
You could do a crossover with the Inhumans. The X Men and Inhumans have some similarities in terms of having special abilities. In the fanfiction, there could be a misunderstanding at first between the two groups. For example, Beast could be fascinated by the Inhuman biology while some of the more hot - headed X Men like Gambit might be a bit more aggressive in their initial interactions. Then they would have to work together to face a threat like an alien invasion.
Another idea is a crossover with the Star Trek universe. The X - Men could find themselves on a Starfleet ship. They might have to deal with the differences in cultures and technologies while also trying to stop Apocalypse from spreading his chaos across the galaxy.
A genetic experiment gone wrong could also be a great plot for the crossover. A mad scientist tries to combine mutant and super - soldier DNA. This creates a new breed of dangerous creatures. The X - Men, with their knowledge of mutants, and the Avengers, with their combat skills and high - tech resources, must work together to contain the threat. Jean Grey's telepathic powers could be crucial in finding the source of the experiment, while Iron Man uses his technology to develop a way to reverse the genetic changes.
Logan (Wolverine) is definitely one of the most popular. His complex past and his brooding nature make him a great character to explore further. Another is Jean Grey. Her transformation into the Phoenix and the internal struggle she faced are rich areas for fanfiction writers to dig into. Magneto is also a favorite. His extreme views on mutant - human relations and his powerful abilities can be used to create interesting plotlines.
One idea could be that Harry has a unique mutant power that Logan initially misunderstands. For example, Harry might be able to manipulate time in small increments, which Logan mistakes for some form of trickery at first. Another could be that they team up to rescue a group of young mutants from a powerful anti - mutant organization. They would have to combine Logan's combat skills and Harry's strategic thinking to succeed.