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.
There are so many fanfictions out there. While I can't point out a particular Piper McLean lemon fanfiction right away, you could also check fanfiction.net. Just be aware that the quality can vary greatly. Look for ones with high ratings and positive reviews from other readers. It might take some time to sift through, but you'll likely find some good reads.
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.
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.
There's a fanfic called 'Jason and Piper: Bond Beyond the Gods'. In this fanfic, their relationship is explored in a unique way, with them facing various mythological threats side by side. Also, 'Piper and Jason: The Love That Endures' shows how their love stands the test of time. 'Jason Grace, Piper McLean: Partners in Destiny' is also a great read as it delves deep into their destinies being intertwined.
A really cool fanfiction idea could be that the demigod world has a special festival related to lemons. Percy and Piper get involved in the festival's preparations. But things go wrong when some evil force tries to disrupt the festival. They have to use their powers and teamwork to save the day. This kind of story would be a great way to explore their relationship and abilities in a different setting, and you might be able to find something similar in the vast world of fanfiction.
Some fanfic writers are part of larger fan communities dedicated to the series that Piper McLean is from. These communities might have discussions about the best writers. You could also try looking at reviews left by readers on different fanfics. If a writer consistently gets positive reviews for their Piper McLean stories, they're likely to be a great find.
One great Percy Jackson and Piper McLean fanfiction is 'The Lost Quest'. It takes them on a new adventure outside of the main series plot. They have to face an ancient evil that was thought to be long gone. The author does a great job of developing their characters further and exploring their relationship in a new and exciting way.
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.
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.
There could be a lemon fanfiction where Piper uses her charm - speak powers in a unique way. For example, she accidentally uses it on Percy during a chaotic moment in a battle, and instead of it causing a problem, it makes them both realize their true feelings for each other. This could then lead to a series of romantic and steamy encounters as they explore their new relationship.
One great Piper McLean fanfic is 'Piper's Adventure'. It delves deep into her character, exploring her relationships and her growth as a demigod. The story is filled with exciting plot twists and really brings Piper to life in a new and interesting way.