There could be a fanfiction where the human signals are actually a form of ancient communication that was lost on Earth but has some deep significance in the wider Mass Effect galaxy. For example, it might be related to an ancient alien visitation on Earth long ago. In this fanfiction, the main character, perhaps a human Spectre, has to uncover the truth behind these signals and how they can be used for good or bad in the current political and military situation in the galaxy.
They can show human determination. For example, if the human signals are a sign of resistance against a powerful alien force, it shows how humans don't give up easily.
Some fanfictions might involve a human character being genetically linked to the Protheans in some way. For example, a human having Prothean DNA that gives them unique abilities. This could lead to a story where they are hunted by various factions who want to study or use their powers. Or perhaps a fanfiction where a human is sent back in time to the Prothean era and has to navigate their complex society while trying not to disrupt the timeline too much.
A great fanfiction could revolve around a human diplomat trying to negotiate a treaty with the quarians. A young quarian gets involved and they end up on an adventure to prove the importance of the treaty to both species. This story could explore the political and social aspects of the Mass Effect universe in relation to human - quarian relations.
One interesting Mass Effect Phantom fanfiction could be about a Phantom's origin story. It might explore how they are trained, what their lives are like before being deployed in the field. Another could focus on a Phantom's unexpected alliance with a group of Shepard's crew, leading to a series of adventures that change the course of the main story. There are also fanfictions that might put a Phantom in a situation where they have to question their loyalty to the Cerberus or whoever they serve.
One interesting 'Mass Effect' lemon fanfiction could be those that explore the romantic relationships between different species in the 'Mass Effect' universe in a more detailed and emotional way. For example, a fanfiction about Shepard and Liara might delve deeper into their connection beyond what the game shows.
Some fanfictions might center around a Geth's relationship with a particular character. Maybe a Geth forms an unlikely alliance with a Krogan. The story could detail how they overcome their differences and work together towards a common goal, while also exploring the unique nature of the Geth's thinking process.
Some fanfictions could focus on the origin of vampires in the Mass Effect universe. It could be a result of some ancient experiment gone wrong, or perhaps they are an alien race that has evolved in a way that gives them vampiric traits. This could tie in with the existing lore of Mass Effect and create a really engaging story.
One interesting 'Mass Effect' baby fanfiction could be about the main characters having to protect a baby with special powers in the Mass Effect universe. Maybe the baby has some unique biotic abilities that draw the attention of both the good and bad forces.
One interesting 'Mass Effect and Naruto' fanfiction could be where Naruto characters are integrated into the Mass Effect universe. For example, Naruto's ninja skills might be used in the context of Mass Effect's combat and exploration. Another could involve the sharing of chakra being a new form of biotic power in the Mass Effect world. There are also likely fanfictions that explore what would happen if Shepard met Naruto and they had to team up to fight a common enemy.
Well, there are fanfictions where the vampire theme is blended with the Mass Effect's complex lore. For example, a story might revolve around a vampire that has ancient knowledge which could be crucial for Shepard in his/her fight against the Reapers. The vampire's immortality and special abilities could add a whole new dimension to the battle strategies. Also, some fanfictions might explore the idea of a vampire race that has been hidden in the Mass Effect galaxy all along and their emergence during a time of great chaos in the story.