One interesting plotline could be them learning to get along despite their past rivalries. For example, they might start to understand each other's insecurities and fears. Another could be them teaming up against a common threat in the wizarding world while living together, which forces them to trust each other. And there could also be a plotline where they discover new magical things together in their shared living space.
Perhaps they live together as part of a magical experiment. While living together, they learn to understand each other's different magical upbringings. Daphne, coming from a pure - blood family, and Harry, with his unique experiences, could exchange knowledge and grow as wizards. For example, Daphne could teach Harry about some pure - blood traditions that are actually useful in certain magical practices, and Harry could share his insights from facing dark wizards.
One plotline could be them trying to keep their relationship a secret from their friends and families at Hogwarts. They might have to be really careful during school events and Quidditch matches to avoid any suspicion.
One interesting plotline could be that they discover their twin relationship early on and try to keep it a secret from everyone at Hogwarts. They might secretly help each other out in classes and with their rivalries against other houses.
A great plotline might involve a magical competition where Draco, Blaise, and Harry are all forced to compete. As they face various challenges, they start to understand each other better. For example, they realize that they all have the same fears about the future of the wizarding world. It could also be a plotline where they are all transported to an alternate dimension and have to rely on each other to get back home.
One interesting plotline could be Harry and Draco being deaged and having to rely on each other in a world that seems new to them again. They might form an unexpected friendship as they don't have the pre - conceived notions from their older selves. For example, they could team up to solve a mystery in Hogwarts that only they, with their combined knowledge from before, can figure out.
Well, in some 'Draco Adopts Harry' fanfictions, a great plotline is how Draco overcomes his past enmity towards Harry. He starts to see Harry as a person in need rather than an enemy. There could be a plot where they work together to uncover secrets about Harry's past that Dumbledore might have hidden. And then, Draco has to protect Harry from those who don't want the truth to come out.
One common plotline is a magical duel over a school competition. Maybe it's for the House Cup, and their fight gets intense as they both use their unique spells. For example, Harry might use his Patronus charm while Draco counters with some dark - arts - inspired hexes.
Perhaps a plot where they all become animagi and have to use their animal forms to solve a mystery in the Forbidden Forest. Draco as a sleek snake, Harry as a stag, and Hermione as an otter, they must navigate the forest's dangers and uncover the truth about a strange magical disturbance.
A great plotline is when they bond over their difficult family situations. Harry has his issues with the Dursleys and Draco has the pressure from his pure - blood supremacist family. They could find common ground in their struggles against the expectations placed on them. This might lead them to support each other in ways that surprise their classmates and teachers alike, like Draco standing up for Harry against Snape's unfair treatment, or Harry helping Draco break free from his family's dark influence.
One possible plotline could be them being paired for a difficult school project at Hogwarts. They start off hating the idea but gradually come to respect each other's skills. Draco might contribute his knowledge of the Dark Arts' history in a more practical way, while Hermione uses her vast book - learned knowledge. Another could be them working together in the post - war wizarding world to reconcile the pure - blood and Muggle - born relations. Draco, coming from a pure - blood family, and Hermione, a Muggle - born, could use their influence to change the views of others.