o ▁subsequently ▁fall ▁in ▁love ▁legit imately . ▁After ▁Leo ▁esc apes , ▁he ▁swe ars ▁on ▁the ▁River ▁St y x ▁that ▁he ▁will ▁return ▁for ▁Cal y ps o . ▁At ▁the ▁end ▁of ▁The ▁Blood ▁of ▁Olymp us , ▁Leo ▁gets ▁back ▁to ▁O gy gia ▁and ▁fre es ▁Cal y ps o ▁although ▁nobody ▁can ▁go ▁to ▁O gy gia ▁twice . ▁ ▁In ▁The ▁H idden ▁Oracle , ▁Cal y ps o ▁comes ▁to ▁Camp ▁Half - B lo od ▁with ▁Leo ▁and ▁reve als ▁that , ▁due ▁to ▁her ▁choice ▁to ▁leave ▁O gy gia , ▁she ▁has ▁become ▁a ▁mort al . ▁She ▁accompan ies ▁Leo ▁and ▁Apol lo ▁in ▁the ▁latter ' s ▁quest ▁to ▁find ▁the ▁O ra cles ▁and ▁stop ▁the ▁Three ▁Em per ors ▁from ▁conqu ering ▁North ▁America . ▁Despite ▁this , ▁the ▁two ▁secret ly ▁attempt ▁to ▁find ▁a ▁normal cy ▁for ▁their ▁lives ▁and ▁later ▁announ ce ▁to ▁Apol lo ▁that ▁they ▁are ▁going ▁to ▁sett le ▁in ▁Indian apolis , ▁although ▁they ▁will ▁continue ▁to ▁help ▁him ▁anyway ▁they ▁can . ▁At ▁the ▁end ▁of ▁The ▁Dark ▁Prop he cy , ▁Cal y ps o ▁stays ▁at ▁the ▁Way station , ▁while ▁Leo ▁goes ▁to ▁warn ▁Camp ▁Jup iter ▁of ▁an ▁imp ending ▁invasion ▁and ▁Apol lo ▁travel s ▁with ▁Meg ▁to ▁search ▁for ▁the ▁E ry th ae an ▁Sy bil . ▁ ▁As ▁a ▁sor cer ess , ▁Cal y ps o ▁can ▁command ▁wind ▁spirits