User blog comment:SayuriDarling/The Mark of Athena Official Discussion/@comment-4388405-20121006181920/@comment-3146930-20121006214446

I still don't think so. They are obviously on the ship from the time that the ship launched (according to Annabeth), but the first time they show any signs of doing anything was right before Leo took Octavian on board (I think that was the first strike). Then Jason and Percy climb on board a moment later after Leo fires and they lay low until the corn field. While you say it was the perfect time for them to attack Jason when his soul left his body (I still don't believe he died), they seemed to have no problem controlling Percy or Leo. It just seems that if they really had appeared to take over Jason in TLH, they would have said something like "We have been here for months now," or some kind of connection to the first book.