Well, Plagg might initially be shocked to discover Hawkmoth's Miraculous. He could try to figure out a way to take it away and keep it from being misused. Maybe he'd hide it in a really strange place only he knows about.
In some fanfictions, Hawkmoths could be defeated by the combined powers of Ladybug and Chat Noir reaching a new level. Maybe they discover a hidden aspect of their Miraculous that gives them an edge, like a super - charged special attack.
A creative way could be through the power of friendship. In the fanfic world, the bond between Ladybug and Chat Noir and their friends could become so strong that it creates a positive energy field that weakens Hawkmoths. It's like the power of love and friendship in some magical stories that overcomes the evil force.
Honestly, it's hard to pick the 'best' writers as there are so many talented ones. However, [writer's name 3] has written some really unique fanfictions. They explore the more philosophical aspects of Tikki and Plagg's existence. And then there's [writer's name 4] who is great at writing humorous fanfictions about the two kwamis. Their dialogues are always on point and make the stories really enjoyable.
One popular theme is the relationship between Tikki and Plagg. They are polar opposites, Tikki being the kwami of creation and Plagg of destruction, and exploring how they interact in different situations can be really interesting. Another theme could be the adventures they have with their holders. For example, when their holders face tough villains, how Tikki and Plagg guide and assist them. Also, stories about their origin and the history of the Miraculous they are associated with are quite popular in fanfiction.
One plot idea could be exploring Hawkmoth's past more deeply. Maybe he had a tragic love story that led him to become so obsessed with the Miraculous. Another idea is to have a character from the fanfiction be a double agent, working for both Hawkmoth and the heroes. This would add a lot of suspense and mystery.
One adventure could be that they accidentally get separated from their holders and have to find their way back. Tikki might use her ability to sense positive emotions to lead the way, while Plagg complains the whole time about being hungry. Along the way, they encounter other kwamis who either help or hinder them.
Well, they could get into all sorts of mischief. Maybe they decide to play a prank on their holders. Tikki could use her positive energy to create an illusion of a delicious macaron that Plagg can't resist, but when he tries to eat it, it disappears. And then Plagg could use his Cataclysm to create little harmless 'disasters' like making a small pile of papers look like they've been completely destroyed, just to make Tikki gasp in surprise.
Perhaps Plagg cries because he feels guilty. He might have made a mistake, like accidentally revealing something to the wrong person about the Miraculous powers or secrets. This guilt could be overwhelming for him. Also, it could be that he's sad about the state of the world in the Miraculous Ladybug universe. There are so many akumas and problems, and he might feel powerless to really change things in a big way.
Hawkmoth himself is very compelling. His complex motives and his transformation from a normal person (presumably) to a supervillain are full of potential for exploration. Ladybug is also great because she has to carry the weight of being the main hero. And Chat Noir with his flirty and brave personality can add a lot of charm to the story.