One possible reason could be that he doesn't like the way science fiction often involves a lot of special effects. He might prefer more dialogue - driven or character - based works.
Maybe he just doesn't find the far - fetched concepts in science fiction appealing. Everyone has different tastes, and he might prefer more down - to - earth or realistic genres.
It could be that Pulp Fiction had some influence on his work or creative thinking. Or perhaps he was just making a random reference for fun.
The ideas in science fiction books are very exciting. They often imagine future worlds, advanced technologies and different civilizations, which can expand my imagination.
One reason could be that the fanfiction is set in a different universe where the characters' personalities are slightly altered. So, this 'new' Harry just doesn't click with Ginny in that version. For instance, if the fanfic is a darker take on the story, Harry might be more jaded and not open to a relationship with Ginny.
Perhaps she has her own vision of their relationship and doesn't want it to be influenced by the often - strange and varying ideas in fanfiction. Fanfiction can be full of outlandish concepts that she doesn't want to be part of. She wants to preserve the unique and special nature of her relationship with Edward as it is in real life.
One reason could be the alteration of McGonagall's personality. If in fanfiction she is made to be overly strict or mean, Harry, who knows her real character, would dislike this new version. In the original series, McGonagall was strict but fair, and any deviation from that in fanfiction might be off - putting to Harry.
One reason could be a change in Dumbledore's personality. If he's depicted as being cold or distant in fanfiction, Harry, who knew him as a mentor figure, might not like it.
The fanfic might be set in an alternate universe where Ron has a different personality. If this new personality clashes with Harry's values or his own personality, then Harry may not like Ron. For example, if Ron is made to be more self - centered in this fanfic, Harry might find it hard to get along with him.
It could be that in fanfiction, Snape has been through some additional trauma or experiences that change his perception of Lily. For instance, if he discovers something about Lily that he doesn't like, such as her involvement in some secret or her having a different side to her character that he finds unappealing. This would cause him to dislike her, as opposed to his more nuanced feelings in the original story.
One reason could be that the fanfiction changes Kakashi's teaching methods too much. Naruto is used to Kakashi's unique style in the original story, and if it's drastically altered in a way that doesn't seem right to Naruto, he might not like it.