A cool concept for 'human becomes twilight fanfiction' is a human who gets transported into the Twilight universe. This person could try to change the story's events. Maybe they befriend Bella and try to prevent some of the dangerous situations she gets into. Or they could end up falling in love with a minor character and create a whole new sub - plot. It could also be that they are turned into a hybrid of a vampire and a werewolf, which is a unique situation not really explored in the original series.
Well, in a 'human becomes twilight fanfiction', you could have a human who is a scientist researching the Twilight phenomena. During their research, they accidentally expose themselves to some sort of essence that starts the transformation process. As they change, they document their experiences, which could be really interesting. They might find that they can communicate with animals like the werewolves or have a special connection to the elements, which are new abilities that add to the fanfiction's intrigue.
One idea could be that Twilight's transformation into an Alicorn brings new responsibilities. She has to learn how to use her enhanced magic powers to protect Equestria from a new and powerful threat that normal magic can't handle. For example, a dark force from a parallel dimension starts seeping into Equestria, and Twilight, with her Alicorn abilities, is the only one who can close the portals.
A plot could revolve around Damon trying to make amends for his past vampire deeds as a human. He could start by helping the victims of his previous vampire attacks or their families. Also, his love life would change. If he was in a relationship with a vampire or a human before, now as a human, new dynamics would emerge. He might worry about being too weak to protect his loved ones.
Perhaps there is a scientific experiment gone wrong that turns Sans into a human. He then has to hide his identity from the other monsters while he tries to find a way to reverse the process. In the meantime, he experiences human sensations like hunger and fatigue for the first time, which makes for some comical and also poignant moments in the fanfiction.
One idea could be that Godzilla, as a human, has to hide his true identity while trying to understand human emotions. He might struggle with the concept of love and friendship, which are very different from his previous existence.
One idea could be that Bella is a vampire from the start but has been in hiding. She could be on a mission to uncover a secret vampire society that has been causing trouble in the Twilight world. This would change her relationship with the Cullens as she'd be more of an equal, not a fragile human.
Another plot could be that Damon becomes human again to be with a human he loves. But once he is human, he realizes that the world he thought he knew as a vampire is very different. He has to start from scratch in building relationships, getting a job, and learning how to live without his vampire powers. He also has to face the jealousy and hatred from some vampires who see his transformation as a betrayal.
One idea could be that Jacob and Renesmee, as humans, have to hide their relationship from the vampire community who might not approve. They could go on adventures together, exploring the human world that Renesmee has just discovered. Another plot could involve them facing some sort of human danger, like a natural disaster or a group of bad humans, and having to rely on each other's unique skills to survive. Jacob's werewolf - like instincts might still be there in a more human way, and Renesmee's special abilities could also play a role in protecting them.
Well, perhaps the human could be transported into the My Little Pony world and gradually take on the characteristics of Twilight. Maybe they start by learning magic like Twilight does, and as they do, they become more like her in personality too, like becoming more studious and dedicated to knowledge.
One interesting concept could be the transformation of human nature. For example, if a human becomes a vampire in the fanfiction, it often involves a change in their moral compass, diet, and relationships. Another concept is the exploration of new powers or abilities. If a human becomes a superhero, the fanfiction might focus on how they learn to control and use their powers. Also, the change in social status is a concept worth noting. A human becoming a royalty in fanfiction would face different challenges like court politics and etiquette.
To make it unique, you could change the setting. Instead of the typical Forks, set it in a big city like New York or Paris. The human's transformation would then be influenced by the different environment. For example, hiding their new vampire or werewolf nature would be more challenging in a crowded city. Another way is to give the human a special ability that is not in the original Twilight. Maybe they can control the weather or have telepathic powers over all supernatural beings.