User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-3146930-20130601104422/@comment-79.122.68.231-20130601143016

I see what you mean. And I could agree with you, but a bluish glow alound only Percy makes me think it is some kind of water (it could be - being in tartarus - some hurtful entity) but look at their legs! They are walking in it, instead of the lava next to them. And the flying monsters (all 5 of them) are flying to the closed doors, and they arent attacting the demigods. Maybe they are also  trying to escape the same thing which are following Percy and Annabeth.