There are indeed some. I've come across a couple where the authors beautifully develop their relationship. They often play with the idea of how their different personalities, Goku's adventurous and friendly nature and Fem Broly's more complex, often misunderstood character, could come together in a romantic context. It's interesting to see how different writers approach this unique pairing.
Well, a major theme is the clash and then the fusion of their personalities. Goku is so upbeat and positive, while Fem Broly may be more brooding. Their relationship development often involves getting past these initial differences. Another theme is the role of their Saiyan instincts. In some fanfictions, these instincts either drive them apart at first or bring them closer as they realize they have a common bond. There's also the theme of loyalty, as they learn to be loyal to each other in the face of various challenges in the story.
One interesting idea could be a story where female Goku and Broly have to team up against a common enemy that neither could defeat alone. Their different fighting styles, Goku's more agile and Broly's brute strength, would create an interesting dynamic in combat.
One popular 'broly x goku fanfic' is 'The Bond Beyond Rivalry'. It explores their relationship in a new way, with unique character interactions and an engaging plot.
Another reason could be that she values the authenticity of the original Naruto narrative. Fanfictions are often the product of fans' wild imaginations and might not align with the official story. She might be a purist when it comes to the Naruto story she is a part of, and thus hates fanfiction that strays too far from the original.
It could be that in the fanfic's plot, McGonagall has some past connection to Harry's enemies. So, her hatred towards Harry is a result of her loyalty to those she has a history with. This would create a lot of drama and conflict within the fanfic's story.
In some fanfictions, Naruto might hate Obito because of Obito's actions in the main Naruto storyline. Obito was involved in many heinous acts like causing the Nine - Tails attack on Konoha which led to the death of many, including Naruto's parents. This could be a reason for Naruto's hatred in fan - made stories.
In fanfiction, there could be a whole bunch of reasons. Artemis is the goddess of the hunt, virginity and the moon. Percy is a son of Poseidon. Their powers and natures are quite different. Perhaps in some stories, Percy's actions, like his impulsive behavior or his way of handling situations, clash with Artemis' more reserved and calculated approach. This could lead to her hating him.
In fanfiction, it could be that the writer wanted to create a new and different dynamic. Harry could hate Remus if there was a love triangle situation involving someone Harry cared about and Remus. For example, if Remus started dating Harry's mother figure in the fanfic world, it could lead to Harry hating him.