How would the other characters' development be different if Luffy dies instead of Ace in fanfiction?

Well, Neville would also be affected. Harry was an inspiration to Neville, and without him, Neville might struggle more with his confidence. However, it could also be a turning point for Neville, where he has to find his own inner strength without Harry's example. Ginny would be heartbroken. She had a special connection with Harry. Her character might become more reserved and less outgoing as she deals with the loss. For the Hogwarts professors, they would have to deal with the loss of a student in a different way. McGonagall, for example, would be deeply saddened and might become more protective of the remaining students. Snape would have a different emotional response as well, as his complex relationship with Harry was a big part of his character development.

The impact would be huge. First, the Straw Hat crew would be devastated. They would likely lose their motivation and purpose. Zoro might go on a vengeful spree. Also, the whole world of pirates would be shaken. Luffy was seen as a rising star, a symbol of hope for many. His death could lead to a power vacuum that other pirates would fight to fill.

Harry would be crushed. He'd feel like he lost a sister. Ron would be in total despair, probably blaming himself. Ginny would be heartbroken too as Hermione was like a sister to her. The Weasley family, who had accepted Hermione as one of their own, would be in mourning. They'd all wonder how they could have prevented it and would be angry at the unfairness of it all.

In this type of fanfiction, one possible plot development could be that Luffy sacrifices himself to save Nami from a powerful and unbeatable enemy. Maybe an enemy with a devil fruit power that can only be countered by Luffy's unique abilities, and in the process of protecting Nami, he exhausts all his strength and ultimately dies.

Nami would be inconsolable at first. Luffy has always been there to protect her, and his sudden death would leave a huge void in her life. She would probably cry for days. As time passed, she would remember all the things Luffy taught her about courage and believing in oneself. Nami would start to take on some of Luffy's leadership qualities in a way. She would be more outspoken about her plans for the crew and more determined to see their dreams through. She would also keep Luffy's memory alive by telling stories of his adventures and his selfless acts to new people they meet on their journey.

In the fanfiction, with Female Luffy, the relationship might have a different dynamic. Maybe there would be a more sister - like bond with Ace. She could be more empathetic towards Ace's past traumas compared to male Luffy. For example, when Ace talks about his father, Female Luffy might offer more emotional support.

Well, Ginny would be devastated. Her relationship with Harry was budding into something more. With Harry gone, she might become more withdrawn. Sirius would feel a sense of guilt towards Ginny, as he's alive instead of Harry. He might try to be there for her like an older brother. The Weasley family as a whole would be in mourning. Their relationship with Sirius would be a mix of gratitude for still being there but also sadness that Harry was gone. And Snape's feelings would be complex. He might feel a strange sense of loss, as Harry was his connection to Lily in a way, and now he has to deal with Sirius still being alive.

Ace would probably be angry at first. He doesn't want Luffy getting involved with such a dangerous person like Blackbeard.

Blackbeard's crew is also a diverse bunch. His more aggressive members like Burgess might be eager to start a fight with Luffy's crew. However, some of the more cunning members could be thinking of ways to use the situation to their advantage. They might try to manipulate Luffy or his crew into making mistakes. And if Blackbeard decides on a certain course of action, his crew would generally follow, but there could be some internal dissent depending on the situation.

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.