He went from being a well-behaved study companion who took punishments in a prince's place, and who shared a close bond with the prince and princess, to becoming a ruthless minister. After an attempted coup failed, he was left in the palace to await his death.
"He sent me so you wouldn't be humiliated at someone else's hands."
"Then why didn't he come himself?"
After being beaten by the prince of old, now a prince in his own right, his wounds became infected and inflamed. His fever wouldn't break, and it eventually damaged his mind.
The memories of over a decade of crimes and wicked deeds were erased, and he returned to the age of thirteen.
Theme: Forgetting and forgiveness