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.
A prevalent theme is the transformation of their relationship. Harry being in a wheelchair forces a re - evaluation of their feelings towards each other. Also, the theme of perseverance is there. Harry perseveres in his daily life in a wheelchair, and Draco perseveres in being there for him. In some fanfictions, there's also the theme of discovery, as Draco discovers new aspects of Harry's personality while he is in this new situation.
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.
One popular 'drarry harry in a wheelchair fanfiction' is 'The Wheelchair Chronicles'. It explores how Harry's new situation in a wheelchair affects his relationship with Draco. Another one could be 'Rolling with Draco' which has a really interesting take on how they interact and support each other.
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 good 'Harry in a wheelchair fanfiction' could be 'Harry's New Path'. It focuses on how Harry overcomes challenges in Hogwarts while in a wheelchair. It shows his determination and the support he gets from his friends like Hermione and Ron.
One idea could be Naruto getting injured during a major battle and having to use a wheelchair while he recovers. His friends could help him adapt and he might find new ways to train in his restricted state.
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.