User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-170.235.245.53-20130514161759/@comment-3146930-20130514230232

Kronos is just one of many Titans. Even if he was defeated, there are bond to be others. It is even said at the end of The Last Olympian that Prometheus went into hiding. Most of the others probably did too.