One interesting idea could be an alternate universe where Naruto and his friends have different elemental affinities. For example, Naruto might have a wind - water combo instead of just wind. This could lead to new jutsu and battle strategies.
There's also 'Naruto's Bet Against the Akatsuki'. In this fanfiction, Naruto bets his life on being able to take down the Akatsuki single - handedly within a year. It has a lot of action - packed scenes and some creative interpretations of Naruto's powers.
Adventure is also a theme. Sometimes the bet leads them into unexpected situations, like exploring a hidden part of Hogwarts or getting involved in a mystery outside the school. This adds an element of excitement and unpredictability to the stories.
Another aspect could be that the leash situation is a way for the author to introduce some comical elements into the fanfiction. Hermione is known for her intelligence and seriousness, so seeing her in a situation where she has to abide by the rules of a lost bet and be on a 'leash' can create some really funny and unexpected scenarios. It can also show how she copes with being in a subservient position, which is very different from her usual role in the wizarding world.
She could have to do all the laundry for a week. This is a common and family - friendly bet consequence. It's a simple task that can be a result of losing a bet.
Well, a plotline might involve a bet about who can better handle a dangerous magical creature encounter. Hermione would rely on her extensive book knowledge, while Fred would use his hands - on experience with magical creatures from his time at the Burrow. It could also be a bet on who can win over a particularly stubborn Hogwarts professor to their side for a school project. Maybe a bet on who can brew the most effective potion in a limited time too.
I'm not aware of any fanfiction with such a title that would be appropriate for all ages. Fanfiction often involves the creative interpretations of fans, but this title seems to have inappropriate implications. It's better to focus on positive and family - friendly fan - created stories about Hermione, like those that explore her academic achievements or her friendships.