In a 'ben 10 x fem xenomorph' fanfiction, the story could start with Ben 10 accidentally stumbling upon the fem xenomorph in a secret government lab. At first, they are hostile towards each other. But as the story progresses, they start to understand each other's motives. The fem xenomorph could be on a mission to find a new home for her species, and Ben 10, being the hero he is, decides to help her find a suitable uninhabited planet where her kind can thrive without causing harm to other species. This would involve a lot of adventure as they face various obstacles and enemies along the way.
It could be a mad scientist who wants to control both Ben 10 and the fem xenomorph for his own evil purposes. He might try to extract their powers or use them as weapons.
Well, it could be really exciting. Ben 10 has all those cool alien forms he can transform into. Imagine him facing off against a Xenomorph. His Heatblast form might be able to use its firepower to keep the Xenomorph at bay. And his Four Arms form could have a physical fight with it. It would be a battle of different kinds of alien powers.
Maybe in the fanfiction, Esther gets into trouble while exploring a dangerous part of the Omniverse. Ben discovers her plight and decides to rescue her. As he does, they find themselves in a situation where they are trapped and have to rely on each other to escape. During this time, they share their hopes, dreams, and fears. Ben realizes that Esther is more than just a friend, and Esther sees Ben in a new light. Their relationship blossoms from there, with them having adventures together and supporting each other in the Omniverse.
In fem Harry x King Xenomorph fanfiction, themes such as discovery and mystery could be present. Harry might be in a situation where she is constantly discovering new things about the Xenomorph and its world. There could also be a theme of transformation. Maybe Harry's encounter with the King Xenomorph causes her to change in some way, either physically or in her personality. And of course, there could be themes related to the struggle between good and evil, depending on how the author portrays the Xenomorph and Harry's role in the story.
One possible plot could be that the female werewolf is an outcast in her own world. Naruto, with his kind heart, befriends her. Meanwhile, the fem Kyuubi has a connection to Naruto due to the Kyuubi within him. They all come together when a common enemy threatens the Hidden Leaf. The werewolf could use her unique abilities, like enhanced strength and speed, to help Naruto in battles, while the fem Kyuubi might offer her own brand of power, perhaps related to chakra manipulation. As they fight side by side, a deep bond forms between Naruto and the two female characters.
Next, her friends could try to find a way to reverse the transformation. They might search for ancient books or consult with wise wizards from other lands. Meanwhile, Fem Harry could be struggling with her new form's physical and mental changes. She might be stronger but also more aggressive. If she accidentally harms someone she cares about in her new state, it would add a lot of drama to the story.
One possible plot could be that Ben 10, with his alien - transforming powers, teams up with Futa Charmcaster in a dimension - hopping adventure. They might face a common enemy that is threatening multiple universes. Ben's various alien forms could provide different skills to combat the threats, while Charmcaster's magic could be used for both offense and defense, and their combined efforts lead to the salvation of the universes.
A cool plot might be that a new villain emerges who has the power to steal the powers of superheroes. This villain targets both Ben's aliens and the Avengers. Ben and the Avengers have to work together to not only stop the villain from stealing more powers but also find a way to get their powers back. Ben's knowledge of his Omnitrix and the various alien weaknesses could be crucial in devising a plan, while the Avengers' combat experience and teamwork skills would be invaluable in facing the challenges along the way.
One possible plot could be that Naruto discovers a hidden Xenomorph lair in the Hidden Leaf Village. He uses his ninja skills to try and figure out how the Xenomorphs got there and what their purpose is. Maybe he has to team up with some of his friends, like Sasuke, to fight off the Xenomorphs before they take over the village.
One possible plot could be that Esther gets caught up in an alien conspiracy in the Omniverse. Ben, being the hero, steps in to save her. As they work together to uncover the truth behind the conspiracy, they start to fall for each other.