User blog comment:Himeyuka/Reyna and Hylla's past/@comment-194.9.188.22-20111206204427/@comment-4515675-20111207175248

Well actually the Amazons didn't exactly make often trips to Camp Jupiter to visit so you can't say that they shared the information. From what I understood they weren't exactly fond of Camp Jupiter and the demigods and the main reason behind them helping the Romans was because Hylla was now queen and Reyna asked for her help but otherwise they probably wouldn't care less if the Romans got defeated.

People swore on the river Styx, the one that did know about it, so even if they knew they weren't allowed to tell anything to anyone. Even the lares didn't let anything slip because Reyna told Percy that. Reyna did hear something, from Octavian but how he found out about it that's a different story, but she thought that they were only stories.