User blog comment:Mickle1026/Rebirth of faded gods?/@comment-3146930-20111008011228/@comment-3146930-20111022190148

But unlike gods, monsters dont have a realm to look over, they rely mostly on belief. Pan died because the wild was being destroyed. Percy claims Briares' brothers faded because they lost belief in themselves. Even then, it is possible that their essence still fades into Tartarus, but doesnt have enough belief to reform. Chiron did say in The Lost Hero that a demigod tried to Google the Gorgons and they appeared. A god without a realm may simply fade or pass their power onto someone else (like Selene, Helios, and Pan)