7 Half-Bloods shall answer the call

Okay, if at this stage you need me to explain that, then what are you even doing here?! Seriously? I mean, come on!

To storm or fire the world must fall

Now, for this one, I think storm could be Camp Jupiter or Jason. Everyone should have picked up by now that in a Rick Riordan book everything means something. Well, almost everything... The color for Camp Jupiter (CJ) is purple. Rick could have had any other color (except orange) and yet he chose purple. Now, maybe I'm reading too much into this, but I learnt in Geography that purple is usually used to represent tempests or STORMS. By extension, this could mean Jason, the son of the god of storms/ lightning.

Fire could be Leo, or the orange of Camp Half Blood (CHB). If you need me to explain how orange or Leo could represent fire, then the plot for BoO is not your biggest problem.

On the other hand, storm could be CHB and fire could be CJ. In SoN Rick makes a big deal about how Mars is the main Roman god, just like in almost every other book he talks about how in Greek terms Zeus is the big guy. I might be wrong, but, for me, in SoN Rick talked too much about Mars being one of the main gods for me to just brush it off. Too much crammed into a chapter or 2, and it was too random, for me. Anyone who's studied ancient Rome and the Romans knows that Mars is one of the main gods. He put too much force on reiterating common knowledge. I mean, come on, the Romans call him Mars Ultor for a reason, right?

An oath to keep with a final breath

This could mean several different things. I think the general consensus is Leo's oath to make it back to Ogygia (and Calypso). And it could be. However we all know that Uncle Rick doesn't like to be predictable (see The Last Olympian). Another theory is Nico. Jason promised him that he'd never tell anyone that Nico was in love with Percy. Maybe something happens, perhaps a run in with the anti-Aphrodite giant or Cupid or something and he refuses to tell? Or Percy with his "we're together" thing. Although, I, personally, hope that NOTHING(!) goes wrong for Percy, Annabeth, or, by extension, Percabeth EVER AGAIN.

And foes bear arms to the doors of death

See: House of Hades

Next time: Character Death...