Months of Lords,Book 3

Kaelith, the Lord of Flame, is both the bringer of destruction and the agent of transformation. His power, as ancient as the volcanoes that burn at the core of the earth, is a force of creation and annihilation. His domain is a land of endless fire, rivers of molten lava, and a sky perpetually filled with ash. He is a figure of both awe and fear-his presence ignites the very air around him, his molten gold eyes blazing with intensity.
Once a mortal man, Kaelith was blacksmith who lost everything in a tragic moment of rage-his family, his village, and his humanity. In a desperate attempt to protect his loved ones from marauders, he unleashed a fire so great it consumed everything. In his grief and remorse, he journeyed deep into the earth, where he met the primal spirit of flame, becoming its chosen avatar, the Lord of Flame.
Though Kaelith is a being of immense power, he is not without compassion. His flame is not only destruction but renewal. It is with this understanding that he encounters a boy-no more than fourteen or fifteen-who, having lost all hope, attempts to end his life by fire. The boy's body is scorched, smoldering with the remnants of his self-inflicted wounds when Kaelith finds him. The flames nearly consumed him, but Kaelith saves the boy, using his fiery power to heal the burns, pulling him back from the brink of death.
The boy's name is Sylas, his spirit broken, his heart as fractured as the charred flesh that marks him. But Kaelith sees something in him-a spark, a flicker of strength beneath the ashes. Rather than letting Sylas fade away, Kaelith decides to train him. The boy will learn to control the flames that almost killed him, to wield fire not as a weapon of self-destruction but as a tool of power and change.Kaelith knows this training may be the only chance Sylas has to rebuild his life.
What's the worst that could happen training a mortal?(Spoiler:The worst)