They might have an epic battle to test Luffy's growth. Shanks could see how much stronger Luffy has become and be proud. Maybe Luffy will show off his new Haki abilities.
In fanfiction, when Sabo and Luffy meet again, they might have an emotional reunion. They could share stories of their adventures since they last saw each other. Sabo might show off his new skills or powers, and Luffy would be excited to see his brother again. They could also plan new adventures together, vowing to face any challenges as a team.
Luffy might be more confident and less like a little kid around Shanks. He has grown a lot, and Shanks would notice this. Their relationship could become more of an equal partnership in terms of respect.
Their relationship would likely deepen. They would have a stronger bond as brothers. They might understand each other's dreams and goals even better. Sabo would support Luffy's pursuit of the One Piece more actively, and Luffy would be more aware of Sabo's role in the revolutionary cause.
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.
There are indeed. Some fanfictions might focus on their adventures together in a new storyline that deviates from the original manga. Others could explore their relationship in a more emotional and character - development - centric way. It really depends on what you're interested in.
One common theme is adventure. They might go on new quests together. Another could be friendship that slowly develops into something more. And sometimes, there's the theme of protecting each other in dangerous situations.
You can also write about their emotional interactions. Maybe Luffy has a moment of self - doubt during their journey, and Marco, being the older and more experienced one, offers words of encouragement. He could share some of his own past experiences of facing difficulties. In return, Luffy's positive energy and unwavering belief in her goals could inspire Marco to look at things from a different perspective. This kind of mutual influence can be a great part of their character interactions.
One plot idea could be that the female Luffy is on an adventure and she meets Marco. They form an unlikely alliance to fight against a common enemy. Maybe a powerful pirate group that is threatening the safety of an island. Along the way, they learn from each other's skills and fighting styles.