Since it's fanfiction, there could be new characters created specifically for this story. Maybe a healer who has a special knowledge of the blacklight virus and its effects on magic. Or perhaps a character who is somehow immune to the virus and becomes crucial in the fight against it.
There might be interesting interpretations of existing characters. For instance, Hermione could be the one who first discovers the nature of the blacklight virus through her extensive research. Harry could be the one who has to face the most dangerous aspects of the virus, using his courage and the power of his scar. Ron might provide the comical relief but also be an important part of the team in finding a solution.
In this fanfiction, we could see the development of side characters. Neville, for example, could step up and use his skills in Herbology to find a plant that might be a key ingredient in a cure for the blacklight virus. And there could be new characters from different wizarding families who have their own motives and secrets related to the virus, adding more depth and intrigue to the story.
The best chapter pointer here is Chapter 140, "Did Jiang Li Finally Crash?". It opens with In the evening, the setting sun was like blood, dyeing the entire earth a... and closes on I was just joking, just joking." Seeing that Wen Jiaojiao had no intention....
A practical answer is Chapter 138, because it turns the idea into a concrete scene. The chapter opens with Is there such a good deal?, adds pressure through From now on, let's get to know each other again." "I'm Wen Jiaojiao,..., and ends on Could it be that the poison also had a side effect of.
Chapter 113 is the strongest chapter-level answer because it starts from The next day, Jiang Lili was up before dawn as usual. and follows through on If things are really as you say, that is indeed quite serious..
If you want the clearest chapter reference, go to Chapter 147. Early on, Xiao Xueyi nodded in agreement after listening.; later, the chapter leans on Su Yinwan seemed to have matured overnight, becoming more and more adept....
If you want the clearest chapter reference, go to Chapter 119. Early on, What is Princess Wen talking about?; later, the chapter leans on I can't understand a word?] [Is this some new meme?] [!!!.
If you want the clearest chapter reference, go to Chapter 157. Early on, It was already the last day of Flash Change in his dream.; later, the chapter leans on His good score had successfully surpassed Jiang Li, making him first in....
A practical answer is Chapter 156, because it turns the idea into a concrete scene. The chapter opens with Flash Change, who was always tardy, was late again today., adds pressure through Why should we get up early to exercise and run, while he, Jiang Yan, gets..., and ends on Soon after, the.
If you want the clearest chapter reference, go to Chapter 158. Early on, Reluctantly, Jiang Yan had no choice but to forcibly join the group for...; later, the chapter leans on A few people lined up and jogged down the narrow path, looking strikingly....
Chapter 121 is the strongest chapter-level answer because it starts from Seeing that Wen Jiaojiao's condition had improved significantly, Director... and follows through on You're supposed to be a man who conquers mountains!] Experienced and....
The best chapter pointer here is Chapter 129, "Spent Millions Only to Drive Traffic to Jiang Li?!". It opens with When they saw that the live chat was full of praise for Jiang Li, those... and closes on With that thought, he smugly turned on his phone..