The best element is often the exploration of disability in a magical world. It shows that even with a physical limitation like needing a wheelchair, magic can still be harnessed. For example, a wheelchair could be enchanted to climb stairs like a charmed stairway at Hogwarts.
It can be developed by focusing on how his daily life at Hogwarts changes. For instance, the staircases that move could be a huge obstacle. So the fanfiction could explore how he and his friends come up with solutions like using magic carpets or levitating charms. Also, his broom - flying might need to be reimagined. Maybe he gets a special broom that can be attached to his wheelchair and he can fly around in a different but still exciting way.
One possible fanfiction could be 'Harry's New Mobility' where Harry gets injured during a battle and has to use a wheelchair for a while. It shows his struggle and how his friends adapt to help him.
One interesting story could be about Harry having to use a wheelchair after a particularly dangerous encounter with a dark wizard. In this fanfiction, he might have to rely on his friends more than ever, and they could come up with magical ways to make the wheelchair more useful, like adding spells for levitation or speed. It could also explore how he copes with his new situation while still being the hero we know.
One interesting 'Harry Potter in a wheelchair' fanfiction could be one where Harry overcomes his new physical limitation with the help of his friends. They might use magic in creative ways to make his wheelchair more than just a hindrance. For example, Hermione could enchant it to fly so Harry can still participate in Quidditch in a way, hovering above the field and using magic to direct the ball.
A plotline could be that Harry is cursed during a duel, and the curse affects his legs, forcing him to use a wheelchair. He then has to find a way to break the curse while dealing with the limitations of the wheelchair.
One interesting 'Harry Potter wheelchair fanfic' might be one where a character who uses a wheelchair has a unique magical ability related to it. For example, they could use their wheelchair as a sort of magical vehicle that can fly or travel through magical portals. Another could be a story where a wheelchair - using character is the key to solving a big mystery at Hogwarts, like they notice things from their unique perspective that others miss.
One common theme is resilience. Harry has to be strong and face the difficulties that come with being in a wheelchair in a magical world. For example, in many stories, he has to figure out how to navigate the moving staircases at Hogwarts.
It also changes the way he is perceived. In normal stories, he is seen as a hero who can physically fight. But now, his heroism might be more about mental strength and using his intelligence. For example, he might use his smarts to outwit villains instead of using physical combat skills. And his friends might have to protect him more physically in dangerous situations.
You can start by searching on fanfiction websites. Look for tags like 'Harry Potter' and 'wheelchair' to narrow down the results. Some popular fanfic platforms include Archive of Our Own (AO3) and FanFiction.net.