One common theme is mutual support. Since both Harry and Neville have had their struggles in the wizarding world, fanfiction often shows them being there for each other. For example, Neville can give Harry advice on herbology, which he's good at, and Harry can offer Neville tips on dealing with bullies like Malfoy.
Yes, there are quite a few. You can check out platforms like Fanfiction.net or Archive of Our Own. Some stories might focus on their adventures at Hogwarts outside of the main plot in the books, like them working together on a special project for a class or exploring the Forbidden Forest.
One possible plot could be that Harry and Neville discover a hidden chamber in Hogwarts that is full of ancient magical plants. Neville, with his love for Herbology, is excited and they both explore it. Along the way, they face some magical creatures protecting the plants and they have to use their combined skills of magic and Neville's knowledge of plants to get through. It could strengthen their friendship as they rely on each other.
Their friendship could lead to some interesting team - ups in Quidditch. Neville might not be the best flyer, but he could be the strategist for Harry. Harry, on the other hand, could execute Neville's plans on the broomstick. This would not only strengthen their bond but also show how their different skills can complement each other.
One great fanfiction could be 'The Unlikely Bond'. It focuses on how Harry and Neville's friendship blossoms in the face of danger at Hogwarts. They support each other through various challenges like dealing with Snape's difficult classes and the looming threat of Voldemort.
I'm not sure specifically if there is a fanfiction titled exactly 'Harry is mad at Neville', but it's very possible. Fanfiction writers often play with different character dynamics. Neville is a character who has his own insecurities and growth throughout the series, and Harry also has his own emotional journey. A story where Harry is mad at Neville could explore their individual personalities and how they resolve their conflict.
Luna Lovegood could also be an interesting addition. Her unique perspective on magic and the wizarding world might bring new ideas to the group. For instance, she could have insights about some of the more mysterious magical creatures or phenomena that they come across, which could be crucial in their quests or battles.
One great fanfiction could be 'The Unlikely Bond'. In this story, Harry and Neville's friendship grows as they face new challenges together in the Forbidden Forest. They discover a hidden magical creature and have to protect it from dark wizards. It shows how their different personalities complement each other.
Maybe a fanfic about how Harry and Neville become best friends during a particularly difficult year at Hogwarts. They support each other through exams, Quidditch matches, and dealing with bullies like Draco Malfoy. Neville could help Harry with his Herbology studies, and Harry could teach Neville some useful Defense Against the Dark Arts spells.
Seamus Finnigan could be an interesting character to put in. His sometimes - explosive magic could create some comical and dangerous situations for the group. And of course, Hagrid. He could introduce them to all kinds of magical creatures and give them advice from his own experiences at Hogwarts.