One possibility could be that Bane, being a centaur, imparts his unique knowledge of the forest and ancient magic to Harry. Harry might grow up with a deep understanding of nature and a different perspective on magic compared to his Hogwarts - educated peers. He could be more in tune with the natural elements and have a wilder, more instinctive approach to magic.
One interesting plot idea could be exploring Bane's backstory more in - depth. Maybe delving into his early days in the prison and how he became the menacing figure we see in the movie. Another could be a different take on his relationship with Talia al Ghul, like if there were hidden motives or unspoken feelings between them.
Bane is a powerful and menacing villain in 'The Dark Knight Rises'. He was trained in the League of Shadows. He comes to Gotham with a plan to destroy the city. He physically and mentally challenges Batman. He breaks Batman's back in a brutal fight, and takes over Gotham, imposing his own brand of cruel justice.
Bane is a formidable villain in 'Batman The Dark Knight Rises'. He was born in the prison of Peña Duro. He was physically and mentally tough. He came to Gotham with a plan to destroy the city. He first broke Batman's back in a brutal fight, which left Batman incapacitated for a while. Bane aimed to bring chaos to Gotham by using the power of the nuclear reactor and also releasing the prisoners, creating anarchy in the city.
One common theme is his magic and power. Writers often explore how Magnus uses his magic in different situations. Another theme is his relationships, like his romantic relationships or friendships. His backstory also features a lot, especially his experiences growing up as a warlock.
Catwoman can also be a popular character to pair with Bane in fanfiction. Her own brand of chaos and thievery can interact in interesting ways with Bane's brute force and strategic mind. Also, Commissioner Gordon could be paired with Bane in a story where Gordon has to outwit Bane in a more cerebral battle, as opposed to the physical battles Batman has with him.
If Harry were raised by Bane, his character would develop a strong sense of loyalty to the centaurs and the forest. He would be more in touch with his animal instincts. His communication skills might be different too, as he'd have to communicate with centaurs and other forest creatures. He could be more reserved around humans, having grown up in a different social structure. And his values would be influenced by the centaur way of life, such as their respect for nature and their prophetic beliefs.
One popular one might be 'The Dark Heir'. In this fanfic, Harry's upbringing by a dark pureblood gives him a very different perspective on the wizarding world. He is taught different magic, often more on the dark arts side, but with a complex moral undertone that makes it interesting.