I'm not sure of specific fanfictions where Hermione is depicted as a thief off the top of my head. But in some fanfiction, this might be part of a plot where she steals a powerful magical artifact to keep it out of the wrong hands, perhaps believing the Ministry or some dark forces are misusing or will misuse it.
It changes her character quite a bit. Normally, Hermione is known for her strict adherence to rules. But as a thief, she becomes a bit of a rebel. She might be more willing to take risks and break the rules for what she believes is a greater good.
Perhaps the thief is a corrupted official in the Yugioh tournament world. He uses his position to steal valuable cards from the best duelists at night. He believes that by having these cards, he can control the outcome of important tournaments and make a lot of money through illegal gambling on the duels. But his actions start to draw the attention of some of the more ethical characters in the Yugioh universe, and they begin to investigate.
Another aspect that makes a good 'The Lightning Thief' fanfiction is the exploration of relationships. This could be the friendship between Percy and his friends, or a new romantic relationship. Fanfictions that delve deeper into how the characters interact with each other on an emotional level can be really captivating. Also, a good fanfiction might introduce new mythological elements that blend well with the existing Percy Jackson universe, like a new type of monster or a different take on an old god.
If Batman was a thief in fanfiction, it could open up all kinds of new storylines. Maybe he's stealing to expose corruption or to gather resources to fight a greater evil that conventional methods can't handle.
There could also be a mysterious outsider from another land. They've heard about the power of the Naruto world's bloodlines and come to steal them. This outsider might have their own motives, like using the bloodlines to strengthen their own people back in their homeland. They would be a completely new and unpredictable element in the Naruto universe, making for an interesting story as the characters try to figure out who this unknown thief is and where they come from.
A new character who is a skilled acrobat could be a great thief. They could use their acrobatic skills to easily get in and out of places unnoticed. Their backstory could be that they grew up in the circus and had to turn to thievery due to some misfortune.
In a fanfiction like this, Hermione as a teacher might be at Hogwarts. She could start a special project about magical creatures and their place in society. Remus, being a werewolf, has a unique perspective. They might collaborate on this project, and during the process, their relationship deepens. The story could also involve some challenges from the more traditional teachers who are skeptical of Hermione's modern teaching methods.
Another alternative is fanfiction that delves into Hermione's post - Hogwarts career. It could be about her working in the Ministry of Magic, making important changes and fighting for the rights of magical creatures. These types of stories highlight her strong - willed and justice - seeking nature.
Lila is often a popular thief character in fanfictions. Given her manipulative nature in the original series, it's easy to imagine her taking on the role of a thief. She could be stealing things to frame Ladybug or gain more power within the school or the city.