User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-7153535-20130628164327/@comment-6064271-20130628181338

I think they did have the pact because most, maybe all the prophecies the oracle says are in the Roman book of prophecies (i cant remember the real name of it), like the prophecy of 7, the romans have known that prophecy for years the greeks knew bout it after the titan war. Also remember that the romans also played a part in theTitan War as Jason defeated a Titan, so maybe the romans thought Jason would be that kid even though he didnt turn 16 when it happened. Or maybe the roman demigods didnt know about that prophecy and the roman gods did know, thats why there isnt alot of roman demigods of the big 3 (if there are they werent mentioned).