The Blood Of Olympus

To me the best part of the entire series was that one chapter when Leo met Calypso on the island. The way Rick Riordan developed the relationship between them...it's just sooo good, and he did it all in a chapter. The beginning of the chapter was when they first met and tensions were high, but at the end of the chapter they couldn't bear parting with each other. First read it when i was 12, then reread it again when I was 15 and this part still trumps every other moment in the series for me.