User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-69.127.161.128-20121113030755

I think Percy will be the one to stay behind because his fatal flaw is being to loyal to his friends. This means he wouldnt let any of his friends stay in Tartarus and he would stay to save them, but leave himself to suffer (though I blelieve he could find a way out).