One possible scenario in such a fanfiction could be that during a potions class, Harry and Draco are forced to be partners. They are making a complex potion, and due to their mutual dislike and lack of proper communication, they mess up the ingredients. The potion explodes, covering them both in a strange goo. This accident could be the start of them seeing each other in a different light, perhaps realizing that they are not so different when it comes to making mistakes.
A great plot point could be that the potions accident results in them being able to read each other's minds. They suddenly have access to each other's deepest thoughts and secrets. This makes them extremely uncomfortable at first, but as they start to understand each other better, they form an unlikely bond. For example, Harry discovers that Draco is under a lot of pressure from his family, and Draco realizes that Harry has his own insecurities despite being the 'Chosen One'.
One possible plot could be that during a potions class, Draco and Hermione accidentally mix the wrong ingredients. This could lead to a magical reaction that causes them to swap personalities. Hermione might start acting like Draco, being more aloof and sarcastic, while Draco could become more studious and rule - abiding like Hermione. They then have to figure out how to reverse the effect while also dealing with the chaos it causes in Hogwarts.
It could improve their relationship. After the accident, they might realize that they have more in common than they thought. For example, they both are very determined when it comes to potions, just in different ways. This newfound understanding could lead to a grudging respect and the start of a friendship.
One idea could be that during a potions class, Harry accidentally mixes the wrong ingredients and creates a potion that makes everyone's voices switch bodies. So Hermione might sound like Ron and vice versa. It would lead to a lot of comical situations as they try to reverse the effect.
One possibility is that a potions accident could cause a time - related mishap. Maybe the potion was supposed to be a simple Sleeping Draught but due to the accident, it creates a time - loop. The characters find themselves repeating the same day over and over until they figure out how to reverse the effects of the botched potion. This could be a really interesting plot device in a Harry Potter fanfic as it would allow for a lot of character development and exploration of different choices within the same day.
Neville could be a great main character for this kind of fanfiction. He's not as confident in potions as some others. So, an accident where he creates a potion that makes all the plants in the Hogwarts greenhouses go wild and start to overgrow and take over parts of the castle would be an interesting story. He would then have to use his knowledge of Herbology to try and control the situation.
The location of Draco's potions shop would also be an interesting point. If it's in a busy wizarding area like Diagon Alley, he'd have a lot of competition but also a high volume of potential customers. However, if it's in a more secluded place, it could attract those who are looking for a more exclusive and private shopping experience for their potion needs.
Power is another theme. Potions can be a source of power in these fanfictions. Draco might try to gain an edge over others by creating or using powerful potions. This could lead to conflicts with other characters as they vie for power too.
Well, it could lead to all sorts of interesting interactions. Maybe they have a friendly chat or a tense confrontation, depending on how the author spins the story.