I really like Calypso as a character and the way you've drawn her is so pretty. I love how in The Battle of the Labyrinth, she was really sweet and kind and gentle with Percy. She fawned over him to some degree and she was overall just such a soft, sweet girl. And in HoH (SPOILERS) she does a 180 degree switch and argues with Leo every spare second she has and in the end, they end up in love despite the fact that they irritate the crap out of each other. I liked her better in HoH to be honest. She's more of a person around Leo than she was around Percy, I think.
(Really, really like the artwork, especially the detail on her hair )