I'm not sure specifically as I haven't read it. It could be about a girl who is in an unexpected situation or has some unusual qualities or experiences.
Another fanfiction idea is that Gekko and Luna Girl are both transported to a different dimension. In this new world, they are the only ones who know each other from their own world. At first, they are suspicious of each other. But as they try to find a way back home, they realize that they need to rely on each other's skills. Gekko's ability to befriend creatures and Luna Girl's knowledge of dark magic could be the keys to their escape. This journey could make them see each other in a new light and form an unexpected bond.
It could be due to their personalities. For example, if one is extremely outgoing and the other is very shy. Their different temperaments would create an unlikely combination for a love story. In such a case, they would have to overcome their differences to be together.
Unlikely friends can get along through mutual understanding. For example, if one is a predator - like a wolf - and the other is a prey - like a sheep - they need to understand that they are different from the norm of their species. The wolf might refrain from its hunting instincts and the sheep might trust that the wolf won't harm it. This could start from a situation where they both face a common threat. Like a forest fire that forces them to rely on each other for survival.
A fanfiction could depict a scenario where Ash is training in a secluded area and suddenly a portal opens up and out comes the Dark Magician Girl. She is being chased by some dark forces from her world. Ash, without hesitation, offers his help. He calls upon his strongest Pokemon to protect her. As they hide from the pursuers, they start to communicate. The Dark Magician Girl is amazed by the Pokemon and Ash is intrigued by her magic. They then come up with a plan to defeat the dark forces once and for all. Ash's Pokemon use their unique moves and the Dark Magician Girl uses her powerful spells to drive away the enemies, forging a strong bond between them in the process.
A really interesting fanfiction could be where Gekko and Luna Girl accidentally switch powers. Gekko now has the power to control moths and fly on the Luna Board, while Luna Girl has Gekko's super - jumping and camouflage abilities. This would lead to a lot of chaos as they both try to figure out how to use their new powers and also deal with their respective friends and foes in the Pj Masks universe. It would be a story full of humor and unexpected twists.
The beauty of Thranduil and modern girl fanfiction is that it allows for a lot of creativity. The modern girl might have a different fashion sense compared to the elves. This could lead to some interesting scenes where she tries to introduce her style, like jeans and a t - shirt, to the elven community, and Thranduil has to deal with the reactions of his people. It's these little details that make the stories so much fun to read.
It could be their social standing. If they were well - respected in the community, like a church leader or a successful businessperson, people would not suspect them easily. They were probably seen as having too much to lose to engage in such a heinous act. Also, if they had a family and a good reputation, others would find it hard to believe they could be a murderer. Their daily life might have been so ordinary and positive - looking on the surface that no one would think they were capable of taking someone's life.