It could be a jealous rival. Maybe someone who is envious of Hermione's intelligence or her popularity among her friends. This person might think that by using a love potion on her, they can make her look foolish or get her into trouble.
There are also fanfictions where a dark wizard or witch gives Hermione the love potion as part of a larger, more sinister plan. They could be trying to use her to get to Harry or Ron, or to gain access to some important information or magical artifact that Hermione has knowledge of.
Obviously, Hermione herself would be directly affected. But also her friends Harry and Ron. They would be worried about her and would do everything they could to help her. Maybe they would also get into some trouble because of trying to fix the situation. For example, they might break some school rules in their attempt to find a cure for whatever the potion accident caused.
She might be initially confused. After all, Draco is usually her adversary. She could be very suspicious and start to investigate what exactly in the potion is causing this strange phenomenon.
A great plot twist could be that the love potion Hermione is exposed to actually has a secondary effect. While it initially makes her seem infatuated, it's secretly stealing her magic. As she becomes more and more 'in love', her powers start to wane. Her friends notice the change in her abilities and suspect foul play. They then have to race against time to find out what's really going on and reverse the effects before she loses all her magic.
One popular fanfiction idea could be that Hermione accidentally consumes a love potion meant for someone else. She then starts acting out of character, perhaps showing an excessive amount of affection towards an unexpected character. This could create chaos in Hogwarts as her friends try to figure out what's wrong and reverse the effects.
One idea could be that Hermione accidentally drinks a love potion meant for someone else. This could lead to all sorts of comical and chaotic situations as she starts acting out of character. For example, she might start chasing after a character she normally has no romantic interest in, like Crabbe or Goyle. It could also create a conflict if she's already in a relationship, say with Ron, and he has to figure out how to reverse the effects.
Obviously, Harry and Hermione are the main characters. They are the focus of the love potion's effect. Whether it's Hermione being affected by the potion and having new - found feelings for Harry, or vice versa, their relationship is at the center of the story.
Obviously Merlin himself could be affected. He's the one with the magic and might accidentally expose himself to the potion. Arthur is also a likely candidate. As the king, if he's affected by the love potion, it would have a huge impact on Camelot. Morgana could also be a character affected. If she were under the influence of a love potion, it could change her plans and her relationships with other characters. And Guinevere too, since she has important relationships in Camelot that could be altered by the potion.
Maybe it's a time - traveling wizard from a far - off era. He comes to Hermione's time and they meet in a place that's a cross - over between different times, like an ancient magical timepiece. Their different perspectives on magic and life draw them together.
If Hermione is given a love potion in fanfiction, it could lead to all sorts of chaos. Her friends would likely notice the sudden change in her behavior. They might first be confused, and then as they figure out it's a love potion, they'd try to find an antidote. Ron would probably be especially affected by seeing Hermione act so differently towards someone else.
Sheen is very likely to be affected. He's impulsive and would probably be one of the first to come into contact with the love potion. His over - the - top personality would make his actions under the influence of the potion really exaggerated, like falling in love with the most random things. Carl could also be affected. He's a bit of a follower, so if Sheen gets affected, Carl might follow suit without realizing it. And of course, Cindy. Since she and Jimmy have that sort of love - hate relationship, if she gets affected by the love potion, it could lead to some really interesting and comical situations between them.