Another important factor is the exploration of the consequences of their love. How does it affect their relationships with other characters like Adrien? And how does it change the overall narrative of the Miraculous Ladybug world? A great fanfic would not just be about their love but also about how this love ripples through the entire story world, creating new story arcs and character developments.
Well, a fanfic about them falling in love might also focus on the internal struggles they face. Gabriel is so focused on his goals related to the Miraculous that he might initially resist his feelings for Nathalie. Nathalie, on the other hand, might be hesitant because of her position as his assistant and the power imbalance. But as the story progresses, these barriers could be broken down, leading to a beautiful and perhaps bittersweet love story.
A good fanfic in this pairing often has well - developed characterizations. It should capture the essence of Gabriel and Vinette's personalities as seen in the original series. For instance, Gabriel's lazy - yet - secretly - caring nature and Vinette's sweet and somewhat naive personality.
Well, perhaps Gabriel discovers that Adrien has been secretly helping Ladybug and Chat Noir. This betrayal, in his eyes, could lead to his akumatization. As an akumatized villain, he might have the ability to create dark illusions of everyone's worst fears. He uses these illusions to try and break the will of the superheroes and force them to reveal their identities. He could also use his power to turn the citizens of Paris against Ladybug and Chat Noir, making it even more difficult for them to operate.
It could be Lila Rossi. Since she's a master manipulator, she could find out about Gabriel's identity as Hawkmoth. Maybe she tries to blackmail him into doing something for her, but Gabriel refuses. In retaliation, she somehow manages to get an akuma and send it to Gabriel, causing his akumatization. Lila might think that by akumatizing Gabriel, she can gain more power and control in Paris.
The plot also matters. It could be a story that takes place within the existing Miraculous Ladybug universe but gives Nathalie a more central role. Maybe she has to make a difficult decision that could change the course of events in the show. Good character development for Nathalie, as well as interactions with other characters like Adrien and Marinette, can make the fanfiction great.
One idea could be that they discover a new Miraculous together. They might be on a mission to find it and in the process, their relationship deepens as they face various challenges. For example, they could encounter an enemy who is also after the same Miraculous and they have to work together to outwit them.
One possible plot could be that Gabriel Agreste, in his search for a way to achieve his goals (maybe related to his fashion empire or his secret identity as Hawk Moth), gets help from an unexpected guide. This guide might be a character who has unique knowledge of the Miraculous or the hidden aspects of Paris. For example, the guide could be an old acquaintance who has connections to the magic that surrounds the Miraculous. They might lead Gabriel to discover new powers or secrets that could change his approach to his plans.
Another motive could be related to his pride. If his son has done something that he sees as a disgrace to the family name, in his over - the - top way of thinking, he might resort to hurting him as a form of punishment. This shows how his ego and his ideas of family honor can lead him to such dark actions.
Maybe the guide is a time - traveler. Someone from the future who has seen the consequences of Gabriel's actions and comes back to try and change the course of events. This time - traveler would know all the ins and outs of what's going to happen and could guide Gabriel towards making better choices. They could show him the destruction his actions as Hawk Moth will cause and offer him an alternative path to achieve his goals in a more positive way.
The deviation from the original relationship dynamic in the books makes it interesting. In the official story, they are just friends, so seeing how a writer can transform that into a romantic relationship is fascinating. It often involves exploring new sides of their personalities.