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.
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.
In this fanfiction, Luffy might initially be in awe of Whitebeard. He could be eager to learn from the great pirate. Maybe they'll team up for a short adventure against a common enemy, like a powerful marine force. Luffy's energy and Whitebeard's experience could make for an interesting dynamic.
Well, one possible plot could be that Luffy, while on one of his adventures, accidentally stumbles upon Dragon in a secret island. They initially don't recognize each other, but then some events unfold that make them realize their connection. Maybe they end up having to team up to fight against a common enemy that is threatening the freedom of the island's inhabitants.
In this fanfiction, it could be that Luffy's mother was thought to be dead but was actually held captive by a powerful enemy. When Luffy finally meets her, she's weak but still full of spirit. She encourages Luffy to keep fighting against the corrupt world of pirates and marines alike. She might also have some inside information about the One Piece, like a clue that she's been holding onto all these years, which sets Luffy on a new and exciting part of his adventure.
Obviously, Luffy and his dad are the most important characters. Luffy, the main character of the original story, is known for his carefree and determined nature. His dad, on the other hand, is a mysterious and powerful figure.
Well, in 'Luffy meets his dad fanfiction', it could be that Luffy's dad teaches him some new and powerful techniques. Maybe they team up to fight a common enemy. This would be a great opportunity for Luffy to bond with his father on a deeper level.
The World Government could be the main antagonist. They see both Luffy as a growing threat to their rule as a pirate and Dragon as a revolutionary. When Luffy and Dragon meet, the World Government might send their strongest agents like the Admirals to stop them from joining forces. The World Government's strict control over the world and their desire to maintain the status quo would put them in direct opposition to Luffy and Dragon.
A powerful and corrupt World Noble could be the main antagonist. They might be trying to stop both Luffy and Dragon's efforts for freedom. The World Noble could have a large military force under their control and be causing chaos and oppression in various parts of the world. This would force Luffy and Dragon to join forces to take them down.