It's likely that Harry Potter himself remains a main character. Since it's a fanfiction related to the Harry Potter series, he would probably be at the center of the story, dealing with the devil - related elements. Hermione and Ron might also be main characters, as they are Harry's closest friends in the original series and would likely be involved in whatever strange events are happening in this fanfiction.
Well, apart from the classic trio, there could be new characters introduced specifically for this fanfiction. Maybe a devil - like figure who is the main antagonist. This character could have unique powers and motives that are related to the devil concept. There might also be some characters from the wizarding families who have a special connection to the devilish happenings, and they become important in the story as they either help or hinder Harry and his friends.
In 'Harry Potter the Devil fanfiction', Harry is surely a main character. But we may also see some minor characters from the original series taking on more prominent roles. For instance, Neville Longbottom could play a crucial part in combating the devil - influenced forces. And there could be a mysterious character, perhaps a dark wizard from the past who has some connection to the devil and resurfaces in this fanfiction to cause chaos. The character interactions among these various characters would be what drives the story forward.
Chapter 349, "Attempting to Cheat, East Ridge's Strength, Lu Yang's Tactics", is the clearest early answer because it turns Zhu Ling's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The five people, including Zhu Tong, were all bowing their heads at... and follows through with If it weren't for Brother Zhu's pressing over the past three years,....
Chapter 77, "Why are you sabotaging me again?", is the clearest early answer because it turns Wen Jiaojiao's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Wen Jiaojiao's reminder calmed Shu Yan down.
Chapter 75, "Master, I didn't mean to bump into you!", is the clearest early answer because it turns Xiao Hu's situation into a concrete plot event. The chapter turns that into something concrete by moving from The ordinary people in the livestream were all stirred up by this...
Chapter 451, "Where Did This Madwoman Come From?", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. The chapter turns that into something concrete by moving from Upon hearing this, the three people turned their heads in unison.
Chapter 105, "He Yun, let me give you a reading", is the clearest early answer because it turns Director Sun's situation into a concrete plot event. Early on, But this did not elicit any sympathy from the woman on the phone; on.... By the end, However, the next second, things took a turn..
Chapter 289, "After all, no one else has designs on Grandpa's inheritance but me", is the clearest early answer because Grandpa gets a payoff that changes the stakes. A useful checkpoint is the way the scene starts with In the pure white room, a man lay motionless on the hospital bed,...
Chapter 223, "Pigpen Live Stream", is the clearest early answer because it turns Director Sun's situation into a concrete plot event. It opens with So, for the first time, Jiang Yan, who had always styled himself as... and closes on The damned Jiang Li was tricking him again!.
Chapter 461, "Team Q Established!", is the clearest early answer because it turns Established's situation into a concrete plot event. The chapter gives readers a real answer by opening on Bai Lu cried while recounting her ordeal to Jiang Li.
Chapter 427, "Wearing Slippers onto the Stage", is the clearest early answer because it turns Tai Fan's situation into a concrete plot event. It opens with He was eager to break free, but Jiang Shixu, the skinny little guy,...
Chapter 13, "Killing the Chicken to Scare the Monkey", is the clearest early answer because the violence around Chicken becomes final instead of hypothetical.