User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-202.156.13.10-20121112141619/@comment-14.139.155.66-20121115094014

Percy is the son of Poseidon, the stormbringer(Chiron called him that on TLT), and he himself is storm and Leo fire and fall may mean the responsibility of the world may fall on either Leo or Percy.

Or maybe frank's fire of,life will have to seal the door. Just like Thanatos could not be released without the fire of life. Other wise the world would fall to Gaea's storm