veritysmaniacal
Paschalis and the others haven't seen Adelaide in a while. Zhade wonders WHY Adelaide left so suddenly, immediately after finding out her long lost sister has returned, and Harrow, Sunni, and Aurora suspect this is another betrayal.
But no, it's much different than that. Adelaide sails off on her own to warn Lori and Rina of their life-threatening upcoming trip to the worst place ever in Greek Mythology (other than Olympus, when Hera finds out Zeus has another demigod child, that is NOT hers.)
2nd book of the Children of the Gods, a continuation of The Child of Apollo series.
See! None of this is canon in the Riordanverse.