One great fanfiction with a jealous Adrien is 'The Green-Eyed Cat'. It really delves into Adrien's feelings of jealousy in a way that stays true to his character. The author does an amazing job of showing how his insecurities surface when he sees Ladybug interacting with other heroes.
One of the best moments is when Adrien finally realizes his true feelings for Marinette. It's a moment of self - discovery that is often written with great emotion in fanfictions. For example, in some stories, he might have a sudden realization during a quiet moment alone, or when he sees Marinette in danger and his heart races not just because she's his friend, but because he loves her.
Character consistency. If the writer keeps Adrien's character traits intact while portraying his jealousy, it stands out. For example, Adrien is generally a kind and selfless person, so his jealousy should not turn him into a completely unrecognizable mean character.
A great fanfiction idea could be that Adrien and Kagami are paired up for a school project. As they work on it, they start to realize that they have more in common than they thought. They could share their dreams and fears, and this new - found closeness might make Adrien question his feelings for Ladybug a bit more.
One possible story could be that Adrien gets akumatized because he feels constantly overshadowed by Ladybug. In this fanfiction, Hawkmoth might prey on his insecurities. As an akumatized form, Adrien could have enhanced physical abilities like super strength and speed. His akumatized look might be a dark version of his Chat Noir costume, with a more menacing appearance.
One popular 'Miraculous Ladybug Adrien Harem Fanfiction' could be 'Adrien's Many Loves'. It often explores different relationships Adrien could have with multiple characters in a creative and interesting way. Another might be 'Adrien's Harem Adventures' which delves into how Adrien manages his relationships within the harem. And 'The Adrien Harem Universe' which creates a whole new world around Adrien and his potential love interests.
This event in the fanfic could also lead to new characters emerging. Maybe someone would try to take on Ladybug's mantle in a different way. Or new villains could rise, seeing the opportunity in the chaos. The magic of the Miraculous might be affected too. Since Ladybug was an important part of the magical balance, her death could have unforeseen consequences on the powers and the Miraculous themselves.
There are many interesting fanfictions out there about Adrien's car in Miraculous Ladybug. Some might focus on Adrien using his car to go on secret adventures while being Chat Noir. For example, he could use the car to quickly reach a location where an akuma attack is about to happen. The car could also be a place where he has some private moments to think about his double life and his feelings for Ladybug.
There's a fanfic called 'Female Adrien's Adventure'. It's set in an alternate universe where Adrien is female. The story focuses on her as a Miraculous holder and how she copes with the responsibilities. It has some really cool action scenes and also some sweet moments where she interacts with her friends. It's a must - read if you like this concept.
There's also 'Marinette's Hidden Talents'. In this fanfic, Adrien discovers some unique skills that Marinette has been hiding. It's a really interesting take as it builds on their characters and the bond between them. It has a lot of cute moments and a bit of mystery too.