Well, it could be the way the author portrays his personality. For example, if they write about his kind - heartedness in a really sweet way. Maybe he's shown helping out a stray animal or being super friendly to fans in the fanfic.
One reason is Jackson Wang's huge popularity. Fans love him so much that they want to create and read fictional stories about him. His charm, talent, and good looks make him a great subject for fanfics.
You can try looking on fanfiction websites like Archive of Our Own (AO3). There are often many fan - created stories about Jackson Wang there. Just use the search function and type in 'Jackson Wang' to find cute fanfics.
Maybe it's because he's so popular and has a charismatic personality that makes him an appealing character for fanfic writers.
A Johnlock fanfic can be considered cute when it focuses on the small, affectionate moments between Sherlock and John. For example, when they take care of each other when one is sick. Simple acts like Sherlock bringing John a warm blanket or John making Sherlock his favorite tea can make the fanfic really cute.
His tsundere - like behavior. In fanfics, Bakugou often acts tough on the outside but has a soft heart deep down. For example, he might grumble about helping someone but still do it, which is really cute.
A Destiel fanfic is cute when it focuses on their innocent interactions. For example, when Castiel is learning about human emotions from Dean. Also, when they share small, affectionate gestures like a gentle touch or a shy smile. It's all about the simple, sweet moments between them.
Often, it's the portrayal of Sherlock's softer emotions. For example, when he shows kindness or protectiveness towards someone, like in fanfics where he takes care of a child or an animal. That's really cute.
The character's personality traits being highlighted in an endearing way can make a Todoroki fanfic cute. For instance, Todoroki's initial shyness or his confusion about normal, everyday things can be really charming. If the fanfic shows him blushing when complimented or his awkward attempts at small talk, it adds to the cuteness factor.
A cute Tangled fanfic often has the main characters, Rapunzel and Flynn, in sweet, everyday situations. For example, just them sharing a simple meal together or taking a walk in the forest. It's also cute when Rapunzel uses her long hair in creative ways to solve small problems, like using it to reach a high - up fruit for Flynn.
Simple things like Naruto's child - like innocence can make a fanfic cute. For example, when he's excited about something as simple as a new type of ramen or when he's trying hard to make friends in a really earnest way.