Perhaps the Muggle Army discovers a way to create their own magical artifacts. They could use their ingenuity and technology to replicate or even improve upon some of the wizarding world's tools. This would not only give them an edge in their fight for equality but also create a whole new dynamic in the 'Harry Potter' universe as the wizards and witches have to come to terms with Muggles having their own form of magic - like capabilities.
One interesting plotline could be Harry trying to adapt to the Muggle world without magic. For example, he might struggle with simple things like using a computer or riding a bike, which would be hilarious. Another could be Harry introducing his wizard friends to Muggle culture, like taking Hermione to a Muggle concert or Ron to a football game.
One plotline could be the Muggle girl introducing Muggle technology to the wizarding world. For example, she might show Harry Potter how a mobile phone works. It creates a lot of humorous and interesting situations as the wizards are often baffled by Muggle inventions.
One plotline could be a muggle stumbling upon the wizarding world during a date. For instance, a muggle and a wizard are on a date in a forest, and the muggle accidentally discovers a magical creature. This then leads to the wizard having to explain the wizarding world to the muggle in a very comical and endearing way.
One possible plotline could be Harry trying to hide his wizarding past from his muggle friends and coworkers. For example, he might accidentally use magic in a moment of panic and then have to cover it up.
One possible plotline could be Harry getting obsessed with a particular Muggle celebrity. For example, he might try to find ways to meet them in the Muggle world, which could lead to all sorts of comical situations as he tries to navigate Muggle customs and technology.
Well, it could be a group of ordinary Muggles who rise to be leaders in the Muggle Army. Maybe there's a tech - savvy Muggle named Tom who uses his knowledge of electronics to find ways to detect magic. He could be one of the main characters.
One possible plotline could be that Harry Potter has to hide his wizarding world from the Muggle he is dating. He might struggle with when and how to reveal his true identity. For example, he could be worried about scaring the Muggle away or getting in trouble with the wizarding authorities for exposing magic to a Muggle.
One interesting aspect is the different perspectives on the wizarding world from a Muggle point of view. Fanfiction often explores how Muggles might react if they discovered the magical world, like in stories where a Muggle accidentally stumbles upon Diagon Alley. Another aspect is the creative interpretations of the existing Harry Potter lore. Writers might come up with new spells or magical creatures that fit within the universe but were not in the original books. Also, the relationships between Muggle characters and wizarding characters can be explored in unique ways, such as a Muggle befriending a Hogwarts student and getting involved in their adventures.
In some fanfics, Dumbledore's Army could be involved in secret missions outside of Hogwarts. For example, they might go on a quest to find a hidden magical artifact that could help in the fight against Voldemort. This would add an element of adventure and mystery to the story.
There are those that focus on how Muggles might react if they were suddenly exposed to magic. For example, a story where a Muggle discovers a magical artifact and has to navigate the strange world of magic with the help of a friendly witch or wizard. In these fanfictions, the interactions between Muggles and wizards are really fascinating.