Did you ever realize that there might not be any monsters down there since they keep reforming. Sure Kronos might be there but I doubt there will be any monsters. Besides we don't see any monsters on the cover it just looks empty (except for Percy and Annabeth).

Percy's the son of the Stormbringer (Poseidon) so it could be Leo, Jason, and Percy to defeat Gaea. Also I think Leo will be the one to close the doors of Death. He is the only one that doesn't have a girlfriend.

Ok well... it's not really a HoH prediction, well it could be, but I think it will more it the last book. So I was reading back through the PJO and HOO Series, blah blah blah and in the TLH, chapter 7 I got a feeling that Chiron was gonna retire, maybe leaving one of seven (Annabeth, Percy more likely) in charge of the actives. Why?
"' I hoped that after he succeed in the titan war and saved mount Olympus, we might have some peace. I might be able to enjoy one finial triumph, a happy ending, and perhaps retire quietly.'"
That's why.

Okay..
Some ideas I have, you don't have to put them but I just needed someone to bounce these off of. :)
1) What about Coach Hedge? What if he dies? I mean Rick never specifies if it's a half-blood that dies. And why else would Coach be there? There has never been a 'chaperone' before (unless if you count Grover...). It just seems like a random move on Ricks part to put him in there. The oath could be his protector oath.

2) Percy is the son of the EARTHQUAKE god. Gaea is EARTH. See what I'm getting at? Some evidence for this could be Frank's great-grandpa being blamed for the earthquake. It introduces the possibility that sons of Poseidon can cause earthquakes.

3) Not a prediction just more of a comment. We do actually know how Nico got out. Gaea brought him out as bait. Without her he would have been stuck.

4) And what's up with the outfits on the cover? Some monster they killed?

5) Finally, the 'oath to keep with a final breath' doesn't have to be one of the seven! It could (hopefully) be a monster! I REALLY want that one to be true, but I doubt Rick will be that nice...

Has it ever occurred to anyone that someone might just go into Tartarus and percabeth will be saved

Actually tartarus (I dun no how 2 spell) is not really a god
Buf im notbsure whether his a titan or not

Rick tweeted that Rachel and Octivian will meet in HoH, but past that he won't say. I think there might be a mini showdown between those two.

OMFG HOW RUDE 1PERCABETHADDICT MAYBE U R THE 1 WHO ISN'T A PERCY FAN HUH?!

Well that can be a possibility that Ouranus would be raised but how? or maybe when? The last book perhaps?

There might be a chance of Hazel dying. In the House of Hades chapter 1 preview it said that Nico told Hazel something about the doors of death that frightened Hazel that she'll have to do.
So...Hazel maybe?

Wouldn't that silvery stuff be the web? You know Arachne's web that was wrapped around her ankle but...NOOOOOOOOOO! ANNABETH AND PERCY CAN'T BREAK UP! AFTER ALL THEY HAVE BEEN THROUGH, HOW CAN THEY BREAK UP?

Wouldn't there be a chance of Gleeson dying in Tartarus cause he loves fighting and pain. He is their chaperon or guardian or whatever and he is suppose to protect them. He may look like a mean coach but deep inside he cares about Percy, Annabeth and rest of the seven

You really like giving readers a heart attack don't you? But these are very likely possibilities but I do know that Rick Riordon will not want an angry mob as everyone knows that fans especially fan/girls/ are dangerous

What if Tarturus, the god, tries to rise with Gaea? I dunno. Maybe there's something that's following Percy and Annabeth in Tarturus and the two get out. Piper charmspeaks whatever that's following them to close the door on the other side.

I really hope your wrong.