Prophecy wise...

If you have check and read the resources on the Percy Jackson wikia (or, if you have actually read all of the books), you should have noticed that most of the prophecies rhyme.

Here's one I came up with that we can use to denote the start of their quest:
[quote][i]Beyond the water's edge you will find,
friend or foe, the chain shall bind.
Beneath the cold bay the dark will rise,
lighting up the flames in her eyes.[/i][/quote]