The Healer's Apprentice

After committing suicide, Merna-now Rain's lingering soul escaped the underworld going against the reincarnation rules of having to wait an entire lifetime to find Caelum at hopes of resurrecting that final hour flame. After a reckless/ cautionless night, king Achlys; ruler of the underworld and lost souls, finds her at last and is determined to bring her back with him for a grand punishment; becoming a grim reaper.

Rightfully so, Caelum argues against the king's unbending rule but the descendant of Hades will not budge so easily, instead he gives Caelum and Rain both an impossible challenge of making Rain a phoenix; a level of healer-ship never achieved. Generous enough, Cae & Rain accept the enigmatic challenge.

Second book after the kingdom of Aragon.