Obviously, Harry Potter would be one of the main characters. He's the central figure in the original series. And Ophis, as the other part of the fanfiction's title, would also be a main character. Her unique abilities and personality would play a big role. Hermione and Ron could also be important as they are Harry's closest friends and would be involved in any new adventures that come about due to Ophis's presence.
The main characters would surely include Harry Potter, who has to deal with the new situation that Ophis brings. Ophis herself is a central figure. Then there are the Hogwarts professors like Snape. Snape's complex personality and his role in the wizarding world would make his reaction to Ophis very interesting. He might be suspicious of her or intrigued by her powers. And we can't forget about characters like Sirius Black if the story takes place during the time he's alive. His loyalty to Harry and his own experiences with magic would add another layer to the story when combined with Ophis's existence.
Chapter 281 is the strongest chapter-level answer because it starts from In his dream, he found himself in a strange world. and follows through on Are you okay?" Jiang Yan covered his wound, the pain causing him some....
Chapter 267 is the strongest chapter-level answer because it starts from Jiang Li had just turned around when she was suddenly embraced by a... and follows through on —However, he was indeed about to experience some misfortune..
Chapter 263 is the strongest chapter-level answer because it starts from Southwest Wildlife Protection Association V: On the evening of July 10 of... and follows through on But when she saw Wen Jiaojiao and Qi Tianyu and others standing up to....
The best chapter pointer here is Chapter 238, "The Guests Were Dumbfounded, The Audience Was Excited". It opens with Jiang Li was actually first on all three leaderboards?! and closes on And, to Zhou Xu's alarm, they did find a problem..
The best chapter pointer here is Chapter 234, "Chasing Wind Youth". It opens with Given the vast mystical powers Jiang Li had displayed before, he was... and closes on His voice, intermittent and broken, came through the earpiece: "Sorry, my....
The best chapter pointer here is Chapter 264, "The Truth". It opens with Jiang Li first reassured her mother, then opened the chat box with Shen... and closes on [Do your faces hurt, you rumormongers?.
A practical answer is Chapter 217, because it turns the idea into a concrete scene. The chapter opens with But Director Sun didn't plan to give her any room to think, he directly..., adds pressure through But," Director Sun took over the conversation, "since you chose the wrong..., and ends on.
If you want the clearest chapter reference, go to Chapter 260. Early on, Yan Dabiao, who deeply felt the sting of deception, flew into a rage and...; later, the chapter leans on Damn bitch, go to hell!" Jiang Li, who was dodging the encirclement of the....
Look to Chapter 223 for the clearest answer. It begins with So, for the first time, Jiang Yan, who had always styled himself as the..., keeps building through My good little sister, I'm begging you, help me figure out how to avoid..., and lands on The damned Jiang Li was tricking him again!.
The best chapter pointer here is Chapter 254, "Madwoman! She is definitely a madwoman!". It opens with Just when everyone thought that Jiang Yan wouldn't last long and would... and closes on A Jiang Li whose head was only filled with books and who never joked or....