The Next Great Prophecy

Percy and Annabeth are relaxing on the beach, when the Stoll brothers run over and takes them to Rachel's cave. Rachel doubles over and begins spewing green smoke:
Three in one sets off with pride
Both sun and moon by her side
The breaking of a sacred oath
Between two friends who appear to loath
An argument at first seems brittle
The earth slowly fades, so very subtle
At cost of wit, courage and determination
Mysteries need be solved to avoid extermination
When five forces come together
A broken truth boy must tell her
Three different breeds repel each other
And fate is saved but at the cost of a near brother

Thirteen years later, Estelle Jackson-Blofis is celebrating her birthday whenstrange things start to happen...