Luffy could change the past in several ways. Firstly, he could use his devil fruit powers in a more strategic way. Since he has the experience of future battles, he knows his opponents' weaknesses better. So, when facing the enemies who were involved in Ace's capture, he can defeat them more easily. Secondly, he could try to influence Ace's relationships. Maybe he can make Ace form stronger alliances with other pirate crews, which would make it more difficult for the Navy to target him. Also, Luffy could try to expose the Navy's secret plans earlier, which would change the power dynamics in the One Piece world and ultimately save Ace.
Well, 'Luffy and Ace: Unbreakable Ties' is a fanfiction that I really like. It focuses on their childhood memories and how those shaped their relationship as they grew up. There's also 'Ace and Luffy's Great Escape' which is full of action. It shows their cleverness in getting out of difficult situations. 'Luffy and Ace: The True Friendship' is a must - read too. It simply and effectively shows the depth of their friendship.
When Luffy and Sabo visit in the fanfiction, it changes their characters in different ways. Luffy becomes more introspective. He starts to think about Ace's values and tries to incorporate them into his own actions. Sabo, on the other hand, becomes more open about his emotions. He had been holding a lot in, but being in the places where Ace was, he can't help but let his feelings out. This makes him more relatable and also helps him to heal some of the emotional wounds from Ace's death.
Dragon saving Luffy would make the World Government see Luffy as an even bigger threat. Since Dragon is their enemy, they'll think Luffy is getting closer to the revolutionary cause, so they'll be more likely to target Luffy aggressively.
In a fanfiction, Ace's own experiences and battles could be related to Luffy's metabolism. Maybe Ace has some knowledge about a special fruit or power that could enhance Luffy's metabolism. He could share this with Luffy, leading to a new adventure where Luffy tries to obtain this thing to boost his metabolism. Also, Ace's death could have an impact on Luffy's metabolism. Luffy could go into a state of shock or extreme grief that either slows down or speeds up his metabolism in an unexpected way.
One great 'Ace Protective of Luffy' fanfiction is 'The Unbreakable Bond'. In this fic, Ace is always on high alert to protect Luffy from any threats in the New World. He uses his fire powers in really creative ways to fend off enemies.
Yes, there are quite a few. Some might focus on female Luffy's adventures alongside Ace in the One Piece world, exploring their unique bond and how they support each other in the face of challenges. These fanfictions can offer new perspectives on the characters and their relationships.
Well, one characteristic could be the focus on a more 'romantic' or 'intimate' relationship between Luffy and Ace, which is often not in line with the original platonic nature of their bond in the source material. However, this is a very controversial aspect as it goes against the typical portrayal of their brotherly relationship.
Character development is key. Fanfictions explore how Ace and Luffy grow under Garp's influence. Maybe Luffy becomes more disciplined in some stories, or Ace learns to be more open - hearted, all thanks to their interactions with Garp and each other.