The act of Harry Potter eating a sucker might be a way to start a chain of events. It could be that this sucker has some special properties that are going to lead Harry into a new mystery or a new relationship with other characters. For example, it might make him irresistible to a certain character, or it might make him the target of a new villain who wants to use the power of the sucker for their own evil plans.
Maybe the author wants to create a humorous situation. Harry Potter is such a well - known and serious character in the original series, and having him eat a sucker just turns that on its head and makes for a really funny scenario. It could also be a way to introduce a new magical item into the fanfiction world that the story then revolves around.
Chapter 727, "Can't Keep Up with the Twists Anymore", is the clearest early answer because it turns Jinli Studio's situation into a concrete plot event. It opens with Jiang Li only posted one picture, but it shut up those haters.
Chapter 665, "Give You a Good Lesson on Behalf of Your Mother!", is the clearest early answer because it turns Sister Liu's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Why should I get so many points?
Chapter 707, "I am Daoist Qingfeng", is the clearest early answer because it turns Su Yinwan's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Su Yinwan hadn't finished her dessert but, feeling agitated, had...
Chapter 721, "Apology", is the clearest early answer because it turns Sha Shaohong's situation into a concrete plot event. The chapter turns that into something concrete by moving from Jiang Li's car had just passed a traffic light when a phone call...
Chapter 837, "Why did she come?!", is the clearest early answer because it turns Gu Shengrong's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The ring is the one Shi Lei just gave her, she really likes it, so...
Chapter 528, "Cursed", is the clearest early answer because it turns Shang Shaobai's situation into a concrete plot event. The chapter gives readers a real answer by opening on The netizens almost unanimously started to sympathize with Jiang...
Chapter 563, "Quite the Confidence", is the clearest early answer because it turns Chen Manman's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Upon learning the result, the four of them stood frozen on the spot,...
Chapter 551, "Who is Reciting "Student Rules"?", is the clearest early answer because it turns Jiang Cheng's situation into a concrete plot event. The chapter turns that into something concrete by moving from Other competitors were already in place, and Qi Tianyu was the last...
A practical answer is Chapter 23, because it turns the idea into a concrete scene. The chapter opens with Although Jiang Li exerted very little strength, Jiang Yan instantly felt..., adds pressure through So the moment the news broke that Jiang Li was entangling with Shang..., and ends on However.
Chapter 705, "Is She Her Own Destined Noble Person?!", is the clearest early answer because it turns Bai Lu's situation into a concrete plot event. A useful checkpoint is the way the scene starts with He Wen was made to laugh by Bai Lu. and follows through with So he's just a side character, huh..