Hogwarts: Weasley Is Our King was a recommended novel, which included supporting actors Fred Weasley and George Weasley. This book can be read on Qidian Chinese website.
The relationship develops in a way that they understand each other's limitations better. George, being carried, realizes that he can count on Fred in difficult situations. Fred, on the other hand, gets to see George in a more vulnerable state. This newfound understanding makes them communicate more openly. They start to plan their future business ideas with more cooperation, knowing that they can support each other through any challenges that come their way in the wizarding world.
In some fanfics, Harry might be able to tell Fred and George apart by their different interests within the story. For example, Fred could be more interested in potion - making experiments that are a bit on the wild side, while George is more into the business side of their joke shop plans. So when they talk about their hobbies or future plans, Harry can distinguish between them. Also, their sense of humor might be slightly different. Fred might crack a certain type of joke more often, like those related to magical creatures in a really absurd way, while George prefers jokes about Hogwarts professors. Through these nuances in their personalities, Harry is able to tell them apart.
Yes, there could be various fanfics involving these characters in the Harry Potter universe. Fanfic writers often create unique stories centered around popular characters like Fred, George and Harry, exploring different plotlines, friendships, and adventures that might not be part of the original books.
One reason could be that they played a particularly mischievous prank on her that went too far. For example, if they made her late for an important exam or meeting with a professor by using one of their wild magical inventions. Hermione, being a stickler for rules and academic achievement, might lose her temper and hex them in retaliation.