User blog comment:Maimer1882/Annabeth is a part of the 7/@comment-3427796-20111024171542/@comment-3146930-20111024232145

The only thing I can think of is when Thanatos is talking about the "Doors of Me," and says that only one kind of demigod can read the clues. He could be talking about Hazel in that statement as Nico was able to find the doors from the other side