At first, their relationship might be a bit tense. Luffy is a carefree pirate, while Dragon is a serious revolutionary. But as they start to talk, they could find common ground in their desire to fight against injustice. Luffy's simple and direct approach to righting wrongs might earn Dragon's respect, and their relationship could gradually turn into one of mutual admiration.
Perhaps Luffy and his crew land on an island that is being used as a base by Dragon's revolutionary army. Luffy, being his curious self, starts exploring and eventually meets Dragon. They could have a conversation about their different but somewhat similar goals. Luffy's goal of finding the One Piece and becoming the Pirate King, and Dragon's goal of overthrowing the corrupt world government. This meeting could lead to an alliance of sorts, with Luffy's crew and Dragon's army working together on a common cause for a short time.
In a fanfiction where Luffy meets Dragon, it could be an emotional moment. Luffy might be shocked to learn that Dragon is his father. Dragon could impart some deep wisdom or a special mission to Luffy. Maybe he would reveal secrets about Luffy's past or the world that Luffy didn't know before. It could also lead to Luffy having a new sense of purpose in his journey to become the Pirate King.
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.
I've heard of a fanfic that focuses on a time when Luffy was a child and Dragon had to make a difficult choice regarding his son. It delves deep into their relationship, showing how Dragon's revolutionary ideals affected his family life. It gives a lot of backstory and really makes you think about their connection.
One popular type of 'One Piece' fanfiction involving Luffy and Dragon might be about their eventual reunion. Since Dragon is Luffy's father, many fans like to imagine the moment when they meet again. In some fanfictions, Dragon could be secretly guiding Luffy's journey without him knowing. This adds an interesting layer of mystery to Luffy's adventures as he is unknowingly following a path his father has some influence over.
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 a One Piece fanfic, an OC (Original Character) as Luffy's rival could be really interesting. This OC might have a unique Devil Fruit ability that directly opposes Luffy's powers. For example, if Luffy has the Gum - Gum Fruit which gives him stretchy abilities, the rival could have a hardening or shrinking ability. This would create intense battles between them as they fight for different ideals on the Grand Line.
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.
A common theme is the exploration of their family relationship. Given that in the original series, their connection isn't delved into much, fanfiction writers often fill this gap. They might write about how Dragon feels about Luffy's growth as a pirate, whether he's proud or worried.