Well, aside from the Marauders like Sirius, Remus, and James, Severus Snape can be a very popular character in Hellfire Club fanfiction. His relationship with the other characters, especially his rivalry with James Potter, can add a lot of drama. Also, Narcissa Malfoy could be an interesting character to include. Her family's influence and her own skills can create some unique storylines within the context of the Hellfire Club. And don't forget about Albus Dumbledore. His presence, whether as an ally or a figure to be reckoned with, can make for some fascinating plot developments.
Well, obviously Sirius Black could be a main character. He was always a bit of a rebel and would fit right in with the Hellfire Club's atmosphere. He could be the one leading the more adventurous and rule - breaking activities within the club.
Hermione is another one. Her intelligence and love for knowledge can lead to interesting interactions with the Winx fairies. She could be the one to figure out how to combine the two different types of magic, or she could be teaching the fairies about the Muggle - born concept in the wizarding world.
Draco Malfoy is also very popular. His antagonistic nature and his own skills in magic make for interesting dueling scenarios. Fanfiction writers might show him in different lights, either as a more complex villain or even as someone who has a change of heart during a duel in the club.
Severus Snape could be a very unique addition to Harry Potter Host Club fanfiction. His brooding and mysterious nature could be used to create a lot of tension and drama in the club. He could be a reluctant host, or perhaps a secret admirer of one of the other hosts. Also, Neville Longbottom could be a great character to feature. His growth from a shy and clumsy boy to a confident young man could be further explored in the host club environment.
Since it's a fanfiction, it could still have Harry Potter as a main character. Maybe Hermione and Ron are also involved. There could also be some original characters created specifically for this fanfiction that are part of the Hellfire group.
One interesting plotline could be the exploration of new magical abilities within the Hellfire Club. Maybe some members discover rare spells or powers that are not part of the regular Hogwarts curriculum. Another could be the relationships between different characters in the club, like how they interact and form alliances or rivalries. Also, a plotline could involve the club getting involved in a mystery that even Dumbledore has trouble solving.
I don't know for sure as I haven't read it. But it could be the founders or leaders of the Hellfire Club.
Sirius Black is often very popular. His mysterious past and his connection to Harry make him a great character to explore in fanfiction. Hermione Granger is also popular as she is intelligent and her actions often drive the plot in the third book.
Harry himself is often very popular. Fanfiction writers like to explore his thoughts and feelings during the events of the second book more deeply. Hermione is also a favorite as she's so intelligent and resourceful. Writers might put her in situations where she uses her wits in new and exciting ways.
Luna Lovegood is beloved in fanfiction. Writers might create stories where she discovers new magical species or has unique adventures. Sirius Black is also very popular. Fan - created stories could be about his time as an Animagus, his relationship with James Potter and Remus Lupin, or his life on the run. Additionally, Ginny Weasley is often a key character in fanfictions, especially those dealing with her relationship with Harry and her own growth as a witch.