One great 'kidd x luffy fanfiction' could be 'The Unlikely Alliance'. It shows how Kidd and Luffy, despite their differences, team up to face a common enemy. Their interactions are really interesting as they both have strong personalities.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). It has a large collection of various fanfictions, including 'kidd x luffy' ones. Just use the search bar and type in the relevant tags.
One popular 'law x luffy x kidd fanfiction' might be those that focus on their adventures together in an alternate universe. For example, a story where they team up against a powerful new enemy that the Straw Hats, Heart Pirates, and Kid Pirates would struggle to defeat alone. This could involve a lot of interesting character dynamics as Law's more calculated nature, Luffy's carefree and bold attitude, and Kid's hot - tempered style clash and blend in the face of danger.
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.
You can start by looking on popular fanfiction websites like Archive of Our Own (AO3). It has a large collection of One Piece fanfictions, and you can use the search function to specifically look for 'law x luffy x kidd' fanfictions. Filter the results by the number of kudos or bookmarks, which usually indicates the popularity and quality of the story.
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.