Disclaimer and ...Stuff

Percy and Annabeth have fallen to Tartarus. They must face numerous struggles and battles to come out on top.
But in Tartarus, they encounter yet again, Kelli, the empousai.
As all hope seems to be lost, a hooded stranger comes to the rescue. A very powerful one. Though he is not a god. Not a Titan. Not a Giant. Not a Primordial. Not exactly a demigod either.
Will they be friends or foe?