User blog comment:SayuriDarling/The Mark of Athena Official Discussion/@comment-3146930-20121005000339/@comment-3146930-20121006193142

As more evidence, The Demigod Diaries has her listed as one of the seven and Gaea appears to need the blood of the prophecy demigods, as she hasn't gone after some random boy and girl demigod. It is even mentioned that Gaea wanted Annabeth, but Arachne said that other could be used.