I'd recommend 'The Secret Mission of Makino and Shanks'. This fanfic has exciting action scenes and a touching emotional core. The author does a great job of capturing the essence of both characters.
Perhaps a plotline where the baby grows up in the care of Makino while Shanks is away at sea. The story could show the baby's longing for its father and how Makino tries to keep the memory of Shanks alive for the child. As the baby gets older, it might start to show an interest in following in Shanks' footsteps, which could create some interesting family dynamics and internal conflicts for both Makino and the child.
One common theme is the long - distance relationship aspect. Since Shanks is a pirate out at sea most of the time, the fanfictions often explore how they maintain their connection despite the distance. Another theme is unrequited love, where sometimes one of them is pining for the other while the other may not be fully aware.
Since the 'lemon' part makes it a bit ambiguous, but if it's a regular fanfiction about Luffy and Makino, it might explore their relationship in the context of Luffy's journey. For example, Makino could be a source of support for Luffy in a more emotional way, like when he has doubts about his role as a pirate. The fanfiction could show how their interactions develop over time and how they influence each other's lives.
One possible plot could be that Emi and Nozomi are in a school setting. They start off as strangers but are paired for a project. As they work together, they discover they have a lot in common, like their love for art. They face some challenges from other students who are jealous of their budding friendship, but in the end, they become best friends and support each other's dreams.
One common theme is friendship. Since Nozomi is part of a group, many fanfics explore her deep bonds with the other members. For example, stories might show how she supports her friends during tough times in their idol careers.
One common theme is friendship turning into something more. Since they are friends in the original series, fanfiction often explores the idea of their relationship evolving romantically.