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.
Luffy is the protagonist of One Piece, with a head full of dreams of being the Pirate King. Ace was his beloved brother, and they had a deep connection. Ace's strength was well - known among pirates. Sabo, on the other hand, was their childhood friend who they thought was dead for a long time. But he returned. The full story involves their childhood days, their separation, Ace's tragic end, and Sabo's re - emergence. It's a story that has elements of adventure, family love, and the pursuit of freedom. Luffy's journey is greatly influenced by his relationships with Ace and Sabo, and their combined story is a big part of what makes One Piece so engaging.
One great 'Ace Sabo Luffy Fanfiction' is 'The Brothers' Bond'. It beautifully explores their relationship, showing how they support each other through various challenges. Another one is 'Sabo's Return'. It focuses on Sabo coming back into Luffy and Ace's lives and how they all readjust. There's also 'Ace and Luffy's Adventure', which takes the three on a fictional journey filled with action and heartwarming moments.
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.
Often, the Marines can be main antagonists. They see pirates as a threat, and with Ace and Luffy being pirates, they would be constantly on the Marines' radar. Marines like Akainu are especially dangerous, as his extreme sense of justice could lead to direct confrontations with the brothers.
Well, it could be that in certain fanfictions, the writers are trying to explore 'what - if' scenarios where Ace and Sabo have some sort of falling out with Luffy. It might be because of jealousy, perhaps they think Luffy is getting more attention or something. But really, this is a huge departure from their normal loving relationship in the main One Piece story.
One great 'Luffy visits Ace' fanfiction could be the one where Luffy travels to Ace's childhood memories. It shows their bond forming from a very young age. Another might be the one where Luffy visits Ace in a dream - like world, and they have deep conversations about their dreams and the meaning of family.
One common theme is brotherhood. Since they are like brothers in the original story, fanfics often explore and strengthen this bond. Another theme is adventure. They are all adventurous characters, so fanfics usually involve them going on exciting quests.
A prevalent theme is the exploration of their relationship in different scenarios. For example, in some fanfictions, the kisses might happen during a time of celebration after a great victory. This shows their joy and how they share their emotions with each other. Also, themes of protection often come up. A kiss can be a way for one to comfort the other when they are in danger or feeling vulnerable.