Fanfiction.net is also a popular platform. However, the quality and content can vary widely. Make sure to read the tags and summaries carefully to find the kind of Annabeth - Piper fanfiction you're interested in. Some stories might be more focused on their friendship, while others could explore different aspects of their characters in unique settings.
A cool fanfiction could be set during a quest. They are sent on a dangerous mission by the gods. Along the way, they encounter various mythical creatures and have to figure out how to defeat them. Their relationship evolves from just being acquaintances to true friends who would sacrifice for each other. Piper might use her powers to distract the enemies while Annabeth formulates a battle plan.
One great fanfic is 'The Adventures of Annabeth and Piper'. It shows their friendship as they go on a quest together in a modern-day setting. They face challenges like dealing with mythical creatures in the middle of a big city. It has a really interesting plot that keeps you hooked from the start.
Some fanfics might also have a theme of power dynamics. Annabeth and Piper have different powers and personalities in the original series. In the lemon fanfics, this can be explored in terms of how they interact with each other in more intimate situations. For example, how their leadership qualities or magical abilities play into their relationship.
Another reason is the relationship between the two characters. Their friendship or potential for a deeper bond is something that fans enjoy exploring. Fanfic writers can develop this relationship in ways that add depth and emotion to the story, making it very appealing to readers.
You can try fanfic platforms like Archive of Our Own (AO3). It has a vast collection of fanfics, and you can simply search for 'Annabeth Chase and Piper McLean' in the search bar. There are likely to be many different takes on their relationship in the stories there.
Another common theme could be the exploration of power dynamics in a relationship. Given Piper McLean's own powers and abilities, how does that play into a romantic relationship? Does it create tension or does it bring them closer? And in the context of 'lemon' fanfiction, this power dynamic can be explored in a more intimate and sometimes even a bit more risqué way, though not always crossing into inappropriate territory.
Another one is 'Under the Stars'. In this story, Piper and Leo find themselves on an unexpected adventure together. The author does an excellent job of portraying their personalities. The story is filled with action, a bit of mystery, and of course, their special bond that makes it a must - read for fans of their pairing.
Since it's a crossover, it combines elements from both Naruto and Piper McLean's universes. However, as it's a 'lemon' fanfiction, it may involve romantic or sexual undertones between the two characters which might be a bit out of the ordinary given their different origins. But in general, it would probably play with their powers and personalities in a new context.
I'm not sure specifically which Piper McLean lemon fanfictions are the best. You can try searching on popular fanfiction platforms like Archive of Our Own. They usually have a wide range of fanfictions related to different characters, and you might find some interesting Piper McLean - related ones there.