Perhaps they work in different departments. Harry could be in charge of the Quidditch team coaching, while Draco is in the administrative side, handling student discipline. They constantly butt heads because of their different approaches. Harry is more lenient and believes in second chances, while Draco is stricter. However, when Hogwarts faces an external threat, they have to put aside their differences and work together to protect the school.
In the fanfiction, they might both be working on a special project at Hogwarts. For example, they are researching a new form of magic that has been discovered in the Forbidden Forest. At first, they are reluctant to work with each other, but as they delve deeper into the research, they realize that each of them brings unique skills and knowledge to the table. Harry's courage and ability to think on his feet, combined with Draco's in - depth knowledge of the Dark Arts (from his family's past), help them make great progress on the project.
One possible plot could be that they meet at a wizarding event in their early childhood. Maybe their families are both attending a magical fair, and the two boys, not yet influenced by the future rivalries at Hogwarts, strike up a friendship over their shared love for magical creatures. They might spend the day together looking at baby unicorns and discussing their favorite magical beasts.
The plot could start with Draco accidentally getting caught in a magical mishap involving a strange plug - like object. This object could have some sort of spell on it that causes his clothes to disappear, leaving him naked. And the story could then revolve around his attempts to get his clothes back while dealing with the embarrassment and the reactions of other Hogwarts students.
At first, they would avoid each other as much as possible. But when they are forced to collaborate on something important, like planning a big event at Hogwarts, they begin to communicate. They argue a lot in the beginning, but then they realize that they have more in common than they thought. They both care about Hogwarts and its future, and this common ground could be the foundation for a better relationship.
In some fanfictions, they might initially dislike each other. Draco, with his pure - blood supremacist upbringing, could look down on Harry. For example, he might make snide remarks about Harry's lack of knowledge about the wizarding world. However, this early encounter could also lead to a different dynamic later at Hogwarts. Maybe Harry would be more prepared to face Draco's taunts because of this prior meeting.
One possible plot could be that Hogwarts, as an entity, watches Draco's memories to understand his internal struggles better. Maybe it's to find a way to help him redeem himself. For example, Hogwarts might see his memories of being pressured by his family to follow Voldemort and then feel sympathetic towards him, leading to some kind of magical intervention to guide Draco onto a better path.
One possible plot is that as the heir of Hogwarts, Harry has some special powers or abilities that he gradually uncovers. He might be able to communicate with the very essence of the school, like the walls and the grounds, and they guide him in his fight against the forces of evil. For example, the castle could show him hidden passages to outwit Voldemort's minions. Also, other characters might react differently to him once they learn of his new status. Some might be jealous, while others would look to him for leadership.
Perhaps there is a mystery in Hogwarts that only Draco and Snape seem to notice. They have to put aside their differences and work together to solve it. It could be something related to an old magic that is starting to have strange effects on the students. As they investigate, they discover things about each other and Hogwarts that they never knew before. This plot would focus on their cooperation and the discovery of new aspects of their characters while staying true to the Hogwarts environment.
In the 'Harry and Draco in Prison' fanfiction, it could be that the wizarding world has a new, strict regime. Harry, being the symbol of the resistance against dark forces, is imprisoned to silence him. Draco, who has always been on the fence between good and bad, is also thrown in prison for not fully conforming. Inside, they initially clash due to their long - standing rivalry. However, as time passes, they realize that the real enemy is the unjust system that put them there. They combine their skills, Harry's courage and Draco's cunning, to start a prison - wide revolt and try to bring about change in the wizarding world.
If Harry were Draco's older brother in this fanfiction, their relationship at Hogwarts would be a total mess - up of the original dynamic. Harry would be constantly torn between the Gryffindor values he adheres to and his family bond with Draco. Draco might start to question his Slytherin - only ideology because of his connection to Harry. For example, they might find themselves in situations where they have to choose between their house loyalties and their new - found brotherly bond, like during the Quidditch matches or the Triwizard Tournament.
Perhaps Harry becomes a professor of Transfiguration. He could introduce new spells and techniques he learned during his adventures. Since he was so good at it during his school days, he would be able to pass on his knowledge and also inspire students to be creative with their transfigurations. He might even have a special project where students try to transfigure something really complex, like a whole building, which he guides them through step by step.