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.
Perhaps Harry uses his wizarding skills in a muggle way. He could use his knowledge of potions to create unique herbal remedies that gain popularity in the muggle world, all while keeping the magical origin a secret. This would add an interesting layer of mystery and secrecy to the story.
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.
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.
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 learning the pure - blood traditions from the Malfoys in a different way than he expected. He might gain a new perspective on the wizarding world's social hierarchy.
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.
Well, perhaps in the fanfic, the Muggle actress is working on a movie about magic, and Harry uses his real - life magic experiences to help her with the role. This could lead to some comical situations where she doesn't quite believe he can actually do magic at first. Also, there could be a plotline where they face some sort of danger from the wizarding world because of their relationship, like dark wizards trying to use the Muggle actress against Harry.
One possible plotline could be Harry exploring his magical abilities in solitude. He might discover new spells or magical artifacts that he keeps to himself. Another could be him building a secret sanctuary where he can retreat from the wizarding world's chaos.
One interesting plotline could be them sharing a flat in London after the war. They support each other through their post - Hogwarts careers, Hermione in the Ministry perhaps, and Harry as an Auror. There are little domestic moments like cooking together or discussing the latest wizarding news over breakfast.
One interesting plotline could be Draco trying to adapt to Muggle technology. For example, he might struggle with using a mobile phone at first, which could lead to some comical situations as he accidentally calls the wrong people or activates functions he doesn't understand. Another plotline could be his interaction with Muggle schools. He might be shocked by the different teaching methods and lack of magic in the curriculum. Also, a potential plotline could involve Draco making Muggle friends and learning about their values, which could be a huge contrast to what he's used to in the wizarding world.