Often, fanfiction writers use the idea of a hidden magical bond. Maybe there was a spell cast long ago that connected Harry and Draco's fates in such a way that Draco becomes his son. Another plot device could be a misinterpretation of a prophecy. The prophecy was thought to mean one thing in the original story, but in the fanfiction, it's re - interpreted to mean that Harry must have a son - like relationship with Draco, which then evolves into Draco actually being considered his son.
One common plot device is time - travel. A character might go back in time and accidentally change something that makes Draco Harry's son. Another is a powerful magical curse or blessing that alters family relations. For example, a curse on the Malfoy family that can only be broken if Draco is 'adopted' into Harry's family in a magical sense.
One common plot device is the introduction of new characters who initially misunderstand Harry, which makes him feel more alone. For example, a new student might come to Hogwarts and, because of rumors or Harry's fame, avoid him or be unkind, adding to his sense of isolation. Another device could be the separation from his friends. Maybe there's a magical accident that sends Harry to a different dimension or a locked part of the castle where he's completely alone and has to figure out how to get back while feeling lonely and scared.
One common plot device is the discovery of ancient artifacts or prophecies that link Harry to Merlin. For example, a magical amulet that was once Merlin's might be found and react only to Harry. Another is the appearance of a character who knew Merlin in the past and recognizes Harry as his reincarnation.
A plot device often used is the threat of separation. Maybe there's a situation where Draco has to go away for some reason, like a mission or a family obligation. Harry's possessiveness kicks in as he doesn't want Draco to leave. This situation can be used to really dig deep into Harry's feelings and show how far his possessiveness can go. He might try to find ways to keep Draco with him, even if it means going against rules or other people's wishes.
One common theme is redemption. Many fanfictions explore Draco's journey towards redemption and how Harry can play a part in it. For example, Draco realizing the error of his ways under the influence of Harry's more noble values.
One common plot device is the discovery plot. Midoriya might find out in a very dramatic way that Harry Potter is his father. For example, he could find a hidden letter or a magical object that reveals the truth. Another device is the mentor - like role of Harry Potter. Since he's so experienced in magic, he could teach Midoriya some special skills related to his quirk that has a magical origin.
In fanfiction, the relationship between Harry Potter and Draco Malfoy can be complex. Some fanfictions might explore their rivalry in a new light, showing how they could potentially grow to understand each other better despite their differences at Hogwarts. For example, they could be forced to work together on a difficult task outside of school, which would make them see each other's strengths and weaknesses.
A common plot device is the exploration of a hidden magical world related to Merlin. Harry, as the heir, is the key to unlocking this world. There might be new magical creatures, spells, and challenges there. He could also face opposition from those who fear his new power or those who want to use him for their own evil purposes. This creates conflict and tension in the story. Additionally, his connection to Merlin could lead to a rewriting of history or a new understanding of the origins of magic in the wizarding world.
One common plotline is the discovery of their brotherhood. It often involves a big reveal, like a hidden letter or a dying relative's confession. Another is them working together against a common enemy. Since they come from different backgrounds, they can bring unique skills to the table. For example, Draco's knowledge of the dark arts and Harry's courage. Also, there's the plotline of them trying to reconcile their different family values and the expectations that come with being part of the Potter and Malfoy families.
In some fanfictions, it could develop due to a common enemy. Maybe there's a new dark force emerging in Hogwarts, and they both realize that they need to put aside their differences to face it. This shared goal makes them rely on each other more, and feelings start to grow as they see the other's courage and determination. Their relationship could grow from a begrudging alliance to a full - fledged romance as they discover new sides of each other.
The power of forgiveness also pops up a lot. Harry, being the hero he is, often has to grapple with whether to forgive Draco for all the mean things he's done in the past. And this struggle and the ultimate act of forgiveness (or not) can be a major part of the story. Fanfictions might explore how this impacts their relationship and the wizarding world around them.