In the PJO series is Frank supposed to be the 'second' Poseidon kid?

[LajaveyonSaunders]

Because it seems everyone has a brother or sister. Nico had Bianca, but she died, and gained a little sister, Hazel. Thaila has her little brother Jason. But Percy has no one, well, except Tyson and Frank. Since Tyson is classified as a monster more than a demigod, does that make Frank Percy's 'Roman' sibling? Or is Rick going to give him a real brother/sister?

 

[Clare]

Frank and Percy are so distantly related that you could not classify them as brothers. One of Frank's ancestors (on his mom's side, obviously) is a child of Poseidon/Neptune, not Frank. He is a son of Ares/Mars. As for Rick Riordan giving Percy a sibling, I think that Tyson would be considered Percy's brother because they are both sons of Poseidon and they are very close. Also, keep in mind that there has not been only one child of any god/goddess in the series. All the demigod characters, whether they have main or supporting roles, have at least one brother or sister, even if that sibling may only be a half-sibling. For example, Annabeth has as many half-brothers and half-sisters as are in the Athena cabin at Camp Half-Blood, but none of them are fully related to her.