Well, in this fanfiction, perhaps the relationship between Luffy and Rayleigh is explored in more depth. We might see Rayleigh sharing his old tales of the Pirate King Gol D. Roger with Luffy. This could inspire Luffy even more in his journey to become the Pirate King. Also, Luffy's character growth in terms of leadership could be a great part. Under Rayleigh's guidance, he might learn how to better lead his crew and make more strategic decisions during battles.
Probably, the main plot is about Luffy's transformation under Rayleigh's training. Rayleigh could be teaching Luffy about the secrets of the Grand Line, the lost history, and advanced combat skills. Luffy then uses what he has learned to face new and more powerful enemies. For instance, he might encounter some strong pirates who are also after the One Piece, and he has to use his newly acquired skills to defeat them and protect his crew. The plot could also involve Luffy's crewmates waiting for him during his training and their own mini - adventures in the meantime.
There's not enough information to know exactly who Rayleigh is. It could be a common name for a person in this context, maybe a local storyteller or someone known within a particular community.
She could be a former pirate captain herself. Maybe she was one of the most feared pirates in her time, and her skills and reputation were passed down to Luffy in some way, even if he didn't know it was from his mother.
They could start with a big hug. Then Shanks might tease Luffy about his still - crazy appetite. Luffy, in turn, could show off his new crew members to Shanks.
In a fanfiction where Luffy meets Roger, it could be an amazing encounter. Roger might see in Luffy the same spirit of adventure and freedom that he had. He could pass on some hidden knowledge about the One Piece or give Luffy a cryptic hint about the true nature of the Grand Line. This meeting could also inspire Luffy even more, fueling his determination to become the Pirate King. It would be a moment full of emotion and significance for both characters and for the entire One Piece universe.
It could be a powerful pirate crew that has a vendetta against either Luffy or Sabo. Maybe they have some history with the Straw Hat Pirates or Sabo's group.
Well, in such a fanfiction, Luffy might gain some valuable advice from Roger. Maybe Roger could share his experiences about the One Piece and the Grand Line, which would inspire Luffy further in his journey to become the Pirate King.
A possible plotline could be a battle scenario. Maybe there's a powerful enemy threatening both Luffy's crew and Marco's group. So they meet on the battlefield and have to quickly figure out how to work together. Their different fighting styles, Luffy's Gum - Gum powers and Marco's phoenix - related abilities, make for an exciting combination in combat.
Well, it could be that Luffy tries to recruit Whitebeard into his crew. Luffy is always on the lookout for strong allies, and Whitebeard with his immense power would be a great addition. However, Whitebeard might laugh it off, seeing Luffy as a young and brash pirate with big dreams but still a lot to learn.