Perhaps a Predator ship crashes on an Alien - infested planet. The lone Predator has to team up with a group of survivors, not just to fight the Aliens but also to repair his ship and escape. Along the way, they discover ancient secrets about both species and how they are more connected than they thought.
A plot could involve a group of humans who are caught in the middle of a war between Predators and Aliens. They form an alliance with a rogue Predator who has his own reasons for wanting to stop the fighting. Maybe there's a powerful Alien queen that the Predators are desperate to kill, and the humans get dragged into that mission.
One idea could be a young human who gets caught in the middle of an alien - predator conflict and has to use their wits to survive. Maybe they form an unexpected alliance with a lone predator who sees potential in the human. Another plot could be an alien - predator hybrid created by some mad scientist, and the two species have to team up to stop this new threat that is stronger and more unpredictable than either of them.
One idea could be an alien with unique telepathic abilities forming a deep bond with a human. The alien might be on a secret mission on Earth and the human gets accidentally involved. They start to understand each other's cultures and values, leading to a friendship that defies the differences between their species.
One idea could be a group of humans caught in the middle of an unexpected alliance between a lone Alien and a young Predator. They have to figure out how to survive while these two usually hostile species work together for some mysterious reason.
One idea could be exploring Alien X's internal conflict between Bellicus and Serena in a new situation. For example, when faced with a moral dilemma on a planet where two species are at war and both have valid reasons for their actions. Another plot could be Alien X having to deal with a powerful new enemy that can somehow disrupt his omnipotent powers. Maybe this enemy has the ability to split Bellicus and Serena's consciousness further, causing chaos within Alien X.
One idea could be exploring the origin of Alien X's powers. Maybe there was an ancient alien race that bestowed these powers and the story could delve into that backstory.
One idea could be the Predators hunting the Sith Lords. The Sith are powerful and dark side users, and the Predators' hunting skills would be put to the ultimate test against them. It would be a battle of wits and power.
Another plot could be a coming - of - age story for a young predator. It's learning how to hunt the prey in a more ethical way. It could be a young lion cub who, instead of just chasing after zebras blindly, tries to understand their behavior and only hunt the ones that are old or sick, in a way that maintains the balance of the ecosystem.
Another common theme is the mystery surrounding the two species. Fanfics often explore the origin and motives of the aliens and predators in more depth. For example, some stories might delve into why the predators hunt the aliens. It adds an extra layer of intrigue to the already complex relationship between the two.
The action and horror elements. The idea of these two fearsome species going at each other or hunting humans is full of action and horror. Fanfics can take these elements and create really exciting and nerve - wracking stories. For example, they can show a group of marines caught in the middle of an alien - predator battle. It's a wild ride of blood, guts, and survival. Also, the different settings, whether it's a desolate planet or a spaceship, add to the overall atmosphere of the story.
One idea could be an Apex Predator coming to Earth and being mistaken for a new mutant. The X - Men initially see it as a threat but then realize it has its own code of honor. For example, it might only hunt the worst of humanity, like criminals. Another plot could involve an Apex Predator getting involved in the conflict between mutants and humans, siding with the mutants as it sees them as the underdogs, much like itself in its own world.