Aliens could originate from a planet that exists in a different dimension. They accidentally stumbled upon our dimension while experimenting with inter - dimensional travel. Their appearance and abilities are very strange to us because they are adapted to their own dimension's laws of physics. For example, they might be able to phase through solid objects or manipulate gravity in ways we can't understand.
An interesting alien origin for a story could be that they are the result of genetic engineering by an ancient and now - extinct race. This ancient race created the aliens for a specific purpose, like to be guardians of a powerful energy source. The aliens have since evolved and developed their own culture, but still carry the genetic imprint of their creators. Their technology might be a mix of what they were originally designed with and what they have developed over time.
One idea could be that the aliens originated from a planet made entirely of crystals. Their bodies are crystalline in nature, and their technology is based on harnessing the power of the crystals. Another idea is that they come from a binary star system, which has led to them having a unique day - night cycle and a very different perception of time.
Unique environments are an interesting element. For example, if the aliens come from a planet that is mostly water but has extreme pressures, like Europa. Their evolution would be shaped by the need to survive in those deep, dark waters. Another interesting part could be their method of reproduction. Maybe they reproduce by splitting like some bacteria on Earth, but in a more complex and intelligent way.
Well, you could do a fanfiction origin story for a side character. Maybe a character who was always in the background but had a really interesting potential origin. For instance, a character who worked in a coffee shop near where the main action happened. Their origin could be that they were actually a spy from another dimension who got stuck there and was waiting for a chance to get back. Or you could focus on the origin of a famous weapon in the story. What if it was created by a long - lost civilization and had powers that no one knew about yet? Also, you could write about the origin of a relationship. How did two characters who are now enemies start out as friends or allies in the past?
A cool concept could be an alternate universe where humans and aliens have been interbreeding for generations. The story could focus on a young character who is part - alien and part - human and their journey to discover their true identity and find their perfect alien mate among different alien races.
One idea could be an alien OC who comes to Earth as an exchange student in a human school. This would lead to humorous and heartwarming situations as they try to fit in with human customs and make friends. They might have strange eating habits or unique ways of communicating that create misunderstandings at first.
One idea could be a story where a group of scientists discover a new type of Xenomorph that has unique abilities, like the ability to camouflage not just visually but also thermally. Another could be a Xenomorph in a post - apocalyptic world where it has to adapt to a new environment filled with human - made obstacles.
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 interesting idea could be how Harry adapts to the alien culture. Maybe he has to learn new languages or customs that are completely different from what he's used to on Earth.
How about an alien invasion that turns out to be a misunderstanding? The aliens thought Earth was uninhabited because they received wrong signals. When they land, they are as shocked as the humans. And then they start a friendly exchange instead of a war.
One idea could be that Amanda discovers a way to communicate with the Alien on a basic level. Maybe she uses her engineering skills to create a device that emits frequencies the Alien can understand. Another could be that Amanda and the Alien form an unlikely alliance against a common enemy, like a group of rogue Weyland - Yutani employees who have their own malicious plans for the Alien.
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.