Some people get ideas for really weird fan fiction when they're in a really creative or dreamy state of mind. Maybe they had a really strange dream about the characters and then decide to write it down as a fan fiction. Or they could be brainstorming with other fans and one person throws out a really wild idea, and they all run with it. It's also possible that they just have a very unique sense of humor and want to create something that will make other fans laugh or be completely shocked by the strangeness.
Reallu weird fan fiction could be about taking well - known characters from a particular fandom and putting them in completely uncharacteristic situations. For example, if it's a superhero fandom, it might have superheroes doing mundane things like grocery shopping in a really strange way. Or it could be about changing the personalities of characters so drastically that they seem like completely different entities within the story.
In some cases, it could be a lack of understanding of appropriate boundaries. They don't see the harm in taking something that is loved by many, like a popular movie or book, and twisting it into something that is sexual and abnormal. They might not have a proper sense of what is acceptable in the realm of storytelling.
People often come up with ideas for the weirdest crossover fanfiction through a process of creative brainstorming. They might start by looking at the core elements of two different franchises. Say, taking the magic system from 'Fairy Tail' and the setting of 'Mad Max'. Then they think about how the characters from one would interact in the world of the other. Also, boredom can play a part. If someone has exhausted all the normal fanfiction ideas for a particular series, they might start to combine it with something completely different just for the fun of it. They might think about how the serious and brooding Batman would react in the wacky world of 'Adventure Time' with its talking candy and magical creatures.
Authors of science fiction often get their ideas from a combination of things. They could be inspired by dreams or nightmares. Some might have a fascination with the unknown, such as what lies beyond our galaxy. They think about the 'what ifs'. What if humans could communicate telepathically? What if there was a planet where gravity worked differently? Also, they may use their own life experiences. If they have traveled a lot, they might write about interstellar travel. If they've had experiences with technology going wrong, they could create a story about a world where technology has turned against humanity.
For me, it often comes from combining different elements. Maybe taking a historical event and adding a fantasy twist, or imagining what would happen if two unlikely characters met. Sometimes, random thoughts or dreams can turn into great story concepts too.
Read a lot. Different books can inspire you with various concepts and themes.
One way is to draw inspiration from your own life experiences and twist them into fictional scenarios. Maybe a memorable trip or a challenging relationship could be the basis for a great story.
Writers get story ideas from all kinds of places. Some draw inspiration from their own lives and experiences, while others might get ideas from reading other books, watching movies, or observing the world around them.
Some authors for novels get ideas from their own experiences. For example, if they've had an interesting travel experience, they might base a story on it. Others might be inspired by historical events. They read about something that happened in the past and think about how to turn it into a fictional story.
Manga artists can come up with ideas by imagining alternate realities or futures. They might combine elements from various sources like history, mythology, or science fiction to create unique storylines. Sometimes, a simple conversation or a news article can spark their creativity.