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.
Ben might initially be very cautious around the Xenomorphs. He's used to his own set of aliens, but these are something entirely different. He could try to communicate with them using his alien forms' unique abilities, but it might not work as the Xenomorphs are more about instinct. The Xenomorphs, on the other hand, would probably see Ben as a threat or a potential host.
The fanfiction might also delve into the power dynamics between the two. Since Xenomorphs are often depicted as very powerful creatures, the male human could be in a position of vulnerability. However, his human intelligence and resourcefulness might be what attracts the female Xenomorph, leading to an interesting dynamic where they both have something to offer and gain from the relationship.
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.
Research is key. Know the lore of the xenomorphs well. Their life cycle, their abilities, and their weaknesses. If you're crossing it over with another franchise, study that too. Once you have a good understanding, start with an interesting hook. Maybe start with the discovery of a xenomorph in an unexpected place in the other universe. Build the story from there, gradually introducing the elements of both universes and how they collide.
In a Xenomorph Fem Harry fanfiction, the female Harry can be a symbol of change in both universes. In the Harry Potter world, being female might make her face different challenges and prejudices, which she can then overcome. With the Xenomorphs, her femininity could be something that intrigues them or makes her stand out. She might use her female intuition to figure out the Xenomorphs' behavior and motives, which could be crucial in any sort of alliance or conflict situation between her and the Xenomorphs.
The pregnancy could be a plot device to introduce new and unknown aspects of the Xenomorph species. Maybe the unborn Xenomorphs have special abilities that are revealed as the pregnancy progresses. Fanfiction writers can use this to build suspense and mystery, keeping readers engaged as they wonder what will happen when the new Xenomorphs are born.
In Amanda Ripley and Xenomorph fanfiction, often she is portrayed as a strong and resourceful character. She might be shown using her wits to survive encounters with the Xenomorphs. For example, she could use her knowledge of the ship's layout to outmaneuver the creatures, just like in the Alien franchise where her family has had to deal with these deadly beings.
Amanda Ripley can be a catalyst for change in the fanfiction. Her actions can lead to different outcomes for the other characters. If she decides to take a risky move against the Xenomorphs, like blowing up a part of the ship they are on, it can either save everyone or put them in more danger. And this makes for an exciting read as readers wonder what she will do next.