Perhaps she is a very traditional character who believes that the official story is the only 'true' story. Fanfic, with its various interpretations and often wild ideas, goes against her view of how things should be between her and Sonic.
Maybe she feels that fanfic often distorts the real relationship between her and Sonic. In fanfic, their characters might be misrepresented, which could make her uncomfortable.
She might hate sonic fanfic because she has her own ideas about how Sonic's story should progress. Fanfics are written by many different people with different interpretations, and perhaps she doesn't agree with the general direction that a lot of fanfics take. Also, some fanfics could be poorly written, which might also contribute to her dislike.
Amy Rose shows her love by constantly chasing Sonic. She is always by his side during his adventures, ready to help. For example, she'll bring him a meal or offer to patch up his wounds.
In some fanfiction, Sonic might be depicted as hating Tails due to a misunderstanding. Maybe Tails accidentally gets Sonic into trouble with some powerful enemy, and Sonic's short - tempered nature in that fictional scenario makes him resent Tails for it.
It could be that a lot of Sonic fanfiction out there is of poor quality. Tails, being a smart character, might not like the way some writers handle the Sonic world in fanfiction, with inconsistent characters or out - of - place plots.
Maybe because she sees the love and effort fans put into it. Sonic fanfic is a way for fans to express their creativity and love for the Sonic universe, so Amy might want to defend that.
Love is a common theme. Since Amy has a crush on Sonic, many fanfics explore their relationship, whether it's her trying to win him over or them finally getting together.
One common theme is the struggle between good and evil. Sonic Exe represents pure evil, and Amy Rose often stands as a symbol of good, trying to fight against it. Another theme is love. Amy's love for Sonic drives her actions in many of these fanfics, even when facing the terrifying Sonic Exe. And there's also the theme of survival. The characters are in a very dangerous situation with Sonic Exe around, so they have to find ways to survive.
Another possibility is that she is protective of her relationship with Sonic. Fanfic might introduce elements that she feels are inappropriate or could potentially damage the 'purity' of what she has with Sonic. It's like she wants to safeguard the special bond they share in the official narrative from being sullied by unapproved fan - created stories.
There are often fanfics that explore their relationship in a more emotional way. For example, a story where Amy Rose has to save Sonic from a dangerous situation and in the process, their bond deepens. These stories often play with their existing character traits, like Amy's determination and Sonic's speed and courage.
It could mean that Amy (presumably a character from the Sonic universe) is standing up for Sonic fan - created fiction. Maybe there are some who are criticizing Sonic fanfic, and Amy is in support of it, perhaps because she values the creativity and passion of the fans who write such stories.