Many readers are drawn to these fanfictions because they can get a sense of a more personal and different kind of love story compared to the main ones in the books. It gives a chance to see Harry in a new light, in a relationship that is less about the overarching battle against Voldemort and more about personal growth and love on an individual level.
One reason is that Daphne Greengrass is a relatively unexplored character in the original series. Fanfiction writers have the opportunity to flesh out her character, give her a backstory, and develop her personality. For example, they can show her as a powerful witch with her own agenda, which is very appealing to readers.
The popularity also lies in the fact that Lily represents a great deal of love and sacrifice in the Harry Potter universe. Fans like to explore how that love would have directly affected Harry as he grew up. They can create stories where Harry gets to know his mother better, and it gives a more complete family dynamic that was missing in the main series. Also, it allows for different interpretations of Lily's character and her magic, which is always interesting for fans to read about.
They are popular because the Dursleys are such complex and disliked characters in the original series. Fanfictions give readers a chance to explore their motives and potentially redeem them. For example, we can understand why they treated Harry so badly in some fanfictions which might be due to their fear of the unknown world of magic.
They're popular because it gives readers a different perspective on Harry's character. Instead of the typical Hogwarts - bound, often restricted Harry, an emancipated Harry has more agency. It allows for new storylines that deviate from the original and can be more exciting.
They're popular because they add a new layer of depth to the characters. We get to see how the beloved 'Harry Potter' characters handle pain and adversity, which makes them more relatable.
Another reason is that Ginny herself is a very interesting character. She's strong, independent, and has her own story. Fanfictions that focus on Harry and Ginny can give more spotlight to Ginny's character and how she complements Harry. This combination of two beloved characters in different and creative storylines is what makes these fanfictions so appealing to a wide range of Potter fans.
They're popular because it's fun to see a different side of Harry. In the original books, he had his struggles, but in these fanfictions, he's often in control. It gives a sense of power and satisfaction to the readers.
Another reason is that it gives a chance to explore different 'what - if' scenarios. What if a character had made a different choice 19 years ago? How would that have changed the present? Fanfiction writers can play around with these ideas, which is really appealing to fans. Also, seeing the growth and development of the original characters' children or the further development of the wizarding world is exciting for fans who have a deep connection to the 'Harry Potter' universe.
They're popular because Sirius is a very complex and beloved character. His story in the original books is full of tragedy and mystery, so fanfiction writers can explore different aspects of his character, like his relationships or his unfulfilled potential.
In a lot of popular Harry Potter fanfictions, Daphne Greengrass is often used to add depth to the Slytherin narrative. For instance, she might be a part of a group that has a different view on the war against Voldemort compared to the more extreme Slytherins. This gives a new perspective on the Slytherin house as a whole.