Harry Potter himself is very common. After all, he's the main character in the original series and is likely to be at the center of any apocalyptic events in the fanfiction. Hermione Granger is also frequently seen as she's smart and resourceful, which are great traits in an apocalypse. Ron Weasley is another one, as he's Harry's loyal friend and has his own set of skills.
Voldemort often appears in 'Harry Potter Apocalypse Fanfiction'. Sometimes he's the cause of the apocalypse, or he's resurrected in a new, more menacing way during the apocalyptic events. Dumbledore also makes an appearance in many, either as a guiding spirit or his past actions having unforeseen consequences during the apocalypse. And Neville Longbottom can be a key character too, as he has shown great courage in the original series and could be a major player in the apocalyptic scenario.
The new generation of students at Hogwarts are very common in these fanfictions. Characters like Teddy Lupin, who has his own unique backstory being the son of Remus Lupin and Nymphadora Tonks. Also, the Weasley - Potter clan members are frequently seen. And in some fanfictions, there are original characters created by the authors, who interact with the well - known Harry Potter characters and add new dynamics to the story.
Another character that could be common is Charlie Weasley. Since he works with dragons in Romania, he can bring a lot of knowledge about dragons to the fanfiction. He might be called back to Hogwarts to deal with a dragon emergency, or be the one to introduce a new type of dragon to the Hogwarts students.
Obviously, Harry Potter himself is very common. He's the central character in the original series, so fanfiction often continues his story or reimagines it. Hermione Granger is also a frequent character. Her intelligence and strong - willed nature make her a great focus for many different storylines. Draco Malfoy is another popular one. Writers like to explore his character further, perhaps showing a more complex side to him than in the original books.
Harry Potter himself is of course very common. He's usually the central figure in these fanfictions. Hermione Granger is also often included as she is Harry's friend and a brilliant witch. Ron Weasley too, as he's part of the trio. Sirius Black might also be a common character since he has a connection to Azkaban.
Definitely Harry. He has so many secrets and needs throughout the series, and the Room of Requirement can be a place for him to fulfill those. For example, he might need a safe place to practice advanced defensive magic against Voldemort. Neville Longbottom can also be a common character. He could use the room to grow and study rare magical plants that he discovers are crucial for some kind of protection against dark magic. Draco Malfoy might be in some fanfiction too. He could be using the room to plot against Harry or to find a way to escape the dark path his family has set for him.
Harry Potter himself is very common. Writers often use him to explore the new and strange pocket dimension. Hermione Granger is also popular as she would be eager to study and understand the unique magic of the pocket dimension. Ron Weasley might be there too, providing his usual humor and loyalty. Dumbledore could be a recurring character as well, perhaps having some prior knowledge about the pocket dimension and guiding the younger characters through its mysteries.
Harry Potter himself is often a central character in such fanfiction. Since he's the main character in the original series, many fanfic authors like to explore how he deals with new or different curses. Hermione Granger is also common as she's very knowledgeable about magic, so she might be involved in researching curses or finding ways to break them.
The most common characters are Harry, Hermione, and Ron as they are the main characters in the original series. However, Voldemort also shows up a lot in these fanfictions. In a time loop, the writers might explore different ways of defeating him or different aspects of his character. Additionally, Luna Lovegood can be a common character. Her unique perspective might help in understanding the time loop better. For example, she might have some off - the - wall theory that turns out to be the key to breaking the loop.
Obviously, Harry Potter himself is one of the most common. Then there's Dumbledore who often plays a role, either as a supporter or as someone with a complex plan. Hermione is also common as she uses her intelligence to help Harry in the trial.
Voldemort is often a key character in such fanfictions. His dark nature and thirst for power can easily lead to situations of carnage. He might be leading his Death Eaters in attacks on Hogwarts or the wizarding community at large.