The Daughter of Poesidon

Percy had always been alone without any halfblood siblings on his dad's side because of the stupid big three pact, but he discovers his dad did have another child that he didn't even tell Percy about. Poesidon of course can't exactly claim his new daughter, if Zeus found out he broke the 'Big Three' act to have no more halblood children twice, things wouldn't be pretty. While she isn't being claimed, Percy begins to suspect who Jade's father might be, and he isn't sure how to react. Part of him is happy that finally he has someone, but at the same time, he doesn't feel special anymore

Jade loves life at Camp Half-Blood, MUCH better than life with her mom. She's creating a new family and she's determined not to lose. She is the only demigod to beat the famous Percy Jackson in a sword fight, and now everyone thinks she's one of the most powerful demigods ever. The only problem is that her life seems to just be a remake of Percy's. She agrees with Luke Castellan about one thing , there's no glory in repeating what others have done.