Well, in the fanfiction, Deku might get a new look that changes how others perceive him. Maybe his friends at U.A. High are really surprised by his new haircut and it could lead to some funny or heartwarming interactions.
The main characters would surely include Deku. Then there could be his classmates from U.A. High. Iida might be one of them, who could have a very formal reaction to Deku's new haircut. And then there could be a new character, like a street - artist who is inspired by Deku's new look and starts to create art based on him.
He might cry a lot. Deku is very emotional, and being cheated on would be a very painful experience for him. He could also get angry, which is rare for him, but this situation would be so unjust that he might not be able to hold it in. He'd probably start to question his self - worth too, thinking that there was something wrong with him that made his partner cheat.
Well, in this fanfiction, Sigyn getting a haircut could be part of a bigger plot. For example, it could be related to a prophecy or a magical event. The haircut might give her some special power or make her a target. Maybe she cuts her long hair short and suddenly she can move more freely in a fight, or perhaps her new look attracts the attention of an important character who has a role to play in her destiny.
In a 'Hermione gets a haircut' fanfiction, perhaps Hermione cuts her hair as a form of rebellion. She's been feeling restricted by the expectations placed on her. So she chops off her long locks into a pixie cut. This new appearance catches Draco's attention in a different way. He starts to see her in a new light and they end up having some interesting interactions that they wouldn't have had before.
Well, maybe Bucky would finally start to feel like a new person. The haircut could be a symbol of his transformation, leaving behind his troubled past and embracing a new identity.
In fanfiction, if Deku gets kidnapped, his friends from U.A. High would likely launch a rescue mission. Bakugo might be especially determined, as much as he tries to hide his concern. They would use their quirks in creative ways to track Deku down.
Well, it's popular because it taps into real - life issues like bullying. Many readers can relate to Deku's experiences on some level. Also, it creates a sense of drama and tension. We as readers are rooting for Deku to come out on top, and the whole process of seeing him deal with the bullies and grow stronger is very engaging. Moreover, it gives fanfiction writers a chance to put their own spin on the character and his backstory, which is always exciting for the fandom.