The Queen and The Guard

Axlan has more or less been taken by the Underground organization against the Templace, an organization that killed the known royal family and are now ruling the kingdom with an iron fist. He and Annabeth fight to destroy them and go on a search to find her parents killers. As they travel,quite a bit is revealed about both of their pasts.
Both of them belong to God's who have granted them with Mana, a force that helps them along the way, but they must trade something earn it. Whether it be permanent service or something more personal, once it's done, it takes a good amount of effort to change back.