User blog comment:Frodo the 9 fingered/A Third Camp?/@comment-4611874-20120812223006/@comment-3146930-20120813215708

Actually, it is kind of the other way around. The Romans seem to have suspicions about possibly Greek demigods, as the gods were Greek before they were Roman and the campers seem to know this (as even Frank, a new recruit, seems to know this so others most likely know it as well). Back at Camp Half-Blood, they never even thought about the existence of another camp until they found out Jason was a Roman demigod and Leo made the connection. As far as a Greek demigod finding Camp Jupiter and leaving, the demigod wouldn't be excepted into camp in the first place without being trained by Lupa and the Mist can be broken. Meaning that any demigod that saw Camp Jupiter would run the risk of exposing them and letting each camp know of the others existence (something the gods swore to try and prevent).