They would probably be very surprised at first. After all, they might not have expected to ever meet Luffy's mother. Then they would be excited to learn more about Luffy's past from her.
The crew's reactions would vary. Allura might be intrigued by how the fanfiction depicts the future of her planet. Coran might be a bit flustered by some of the unorthodox ideas. But overall, they would probably find it an interesting read and might start debating the plausibility of the events described in the fanfiction.
The crew of the Battleship Yamato in a time - travel scenario would have mixed reactions. Some might be excited to explore this new world. Others would be fearful of the unknown. They would have to adapt to the new technologies or lack thereof in the new time they are in. For example, if they land in a primitive era, they would have to figure out how to survive without modern supplies. And if they land in a more advanced era, they would have to deal with the culture shock of seeing things far beyond their understanding.
Nami would probably be devastated. She has been with Luffy through so much, and his death would be a huge blow. She might become more withdrawn and serious, as Luffy was often the one to bring out her lighter side.
The Harry Potter fandom is great for oc fanfiction. There are so many aspects of the wizarding world to explore, like creating a new student at Hogwarts with unique magical abilities. Another good one is the Star Wars fandom. You can create original characters within the vast galaxy, perhaps a new Jedi or a smuggler in a far - off system. The Marvel Cinematic Universe is also a top choice. You could develop an original superhero or villain with powers related to the existing lore.
One of the top fandoms for fanfiction is the Doctor Who fandom. With its time - traveling and space - exploring premise, the possibilities are endless. You can create new adventures for the Doctor and his companions, or introduce new alien species. The Supernatural fandom is also very popular. There are so many different mythologies and creatures in the show that you can base your fanfiction on. And then there's the Percy Jackson fandom. It combines Greek mythology with modern - day settings. You can write about new quests for demigods, or explore the relationships between different characters from different cabins at Camp Half - Blood.
For the Straw Hat crew, it would be a major shift. Sanji would be beside himself with excitement, always eager to please and protect. Zoro would have a complex reaction. He might be a bit more gentle in his challenges to her but also be on high alert to make sure no one takes advantage of her. Nami would be thrilled to have a female companion on board. She could teach Luffy about things like haggling in a more feminine way. Usopp would be the one to spread the news around the ship in his own humorous way. Chopper would study if there are any health differences for a female Luffy. Franky would be focused on making the ship more comfortable for her, like adding softer seating areas. Brook would be using his skeletal charm to make her laugh and keep the crew's spirits high.
Sanji would go all out in cooking the most nutritious and delicious meals for Usopp to help him recover. He might also be a bit overprotective, not allowing anyone to disturb Usopp while he's eating. Chopper would be in full - on doctor mode. He'd be constantly checking Usopp's vital signs, giving him medicine, and trying to figure out the cause of the sickness. Robin would be quietly researching any possible cures or causes, using her knowledge of history and ancient texts.
The Straw Hat crew would probably be very surprised at first. Nami might worry about how Hancock's presence would affect their finances, since Hancock is used to a more luxurious lifestyle. Usopp would be in awe of Hancock's beauty and powers. Chopper would be excited to have Hancock around, as she could potentially teach him about different kinds of medicine from Amazon Lily. Zoro might be a bit skeptical at first but would come to accept it as long as Luffy was happy.
Luffy would probably be excited. He loves having new and interesting people on his crew. Zoro might be a bit cautious at first but would come to respect Naruto's fighting skills. Nami would see Naruto as someone who could be useful for his abilities.