I really liked a fanfic called 'Fire and Water'. It delved deep into the relationship between Leo and Percy. It showed how their different powers could work together in a really creative way. There were some great action scenes and also some really touching moments of friendship. It was a long read but definitely worth it as it explored the characters in depth and took them on a journey that was both exciting and full of character growth.
There's this fanfiction titled 'Alliance of the Demigods'. In this one, Leo and Percy face a common enemy. The story is filled with twists and turns. The author's description of the demigod world and how Leo and Percy interact within it is really engaging. It's a fast - paced read that keeps you on the edge of your seat.