Definitely Tikki and Plagg. These Kwamis are essential to the Miraculous universe. Their interactions with Cat Noir and Ladybug, as well as their own little quirks and personalities, can make for really fun fanfiction. Additionally, Sabrina, Chloe's sidekick, can be an interesting character to include. She could have her own story of breaking free from Chloe's control or getting involved in the hero - villain drama in some unexpected way.
One idea could be that Cat Noir and Ladybug get transported to an alternate Paris where the roles of heroes and villains are reversed. They have to figure out how to adapt and set things right. Another could be a time - travel plot where they go back in time to prevent Hawkmoth from ever getting his hands on the Miraculous in the first place. And a third idea is that there is a new villain who can manipulate emotions, and Cat Noir and Ladybug have to not only fight the physical battles but also the emotional turmoil this villain causes among the citizens.
Obviously, their best friends like Alya and Nino would be there. Alya could be Ladybug's maid of honor, and Nino could be Cat Noir's best man. Also, all the other superheroes they've worked with in Paris would be invited. And of course, their families, if their identities were revealed by then. Maybe even some of the citizens of Paris who have been saved by them over the years would show up to celebrate this special occasion.
Well, in some fanfictions, Hawkmoth might use false promises. He could promise Cat Noir something like the power to save a loved one in exchange for his help.
One aspect could be the over - dramatization of negative emotions. In some fanfictions, Cat Noir might be depicted as overly brooding or having extreme self - doubt that goes beyond the character's original portrayal. This can create a darker and more angsty tone.
No, it is not appropriate. 'Miraculous Ladybug' is a popular animated series aimed at a wide audience including children. Writing sexual fanfic about the characters goes against the family - friendly nature of the show and can be considered inappropriate and disrespectful to the original work and its fans.
How about a fanfiction where there's a new villain in Paris who has the power to nullify the Miraculous? Ladybug and Chat Noir would have to find a way to regain their powers or find new ways to fight this powerful enemy without relying on their usual abilities.
Perhaps Hawkmoth tells Chat Noir because he believes Chat Noir can understand his motives or is trying to manipulate him into giving up the miraculous.