Becoming the Tyrant's Teacher

[I've had some new ideas, so I might rewrite the whole thing] Yuan Zhaoyue was a goddess who descended to the mortal realm to undergo a trial. She had to assist a wise ruler in bringing peace to the land before she could return to the Immortal Realm. But she misjudged someone, and came to a tragic end. When she awoke from a long dream, she was still the lofty Imperial Tutor. By tradition, the Imperial Tutor had to choose a prince to cultivate. A group of princes knelt in her courtyard, anxiously begging forgiveness. Yuan Zhaoyue looked toward the prince kneeling at the end of the line. In her previous life, after she had made her choice, this low-born Seventh Prince had been sent to an enemy nation as a hostage. In the end, despite being no more than a hostage, he seized the enemy throne and became one of the great powers among the nations. If she had to help a wise ruler either way, wouldn't it be better to choose someone who could take the throne himself? As it turned out, Yuan Zhaoyue had made the right gamble this time. In just ten years, her new student, her latest tool, unified the land. She completed her trial and successfully returned to the Immortal Realm, where she could go back to her goddess's carefree life of eating and waiting to die. She was the very picture of a winner. At the time, Yuan Zhaoyue had no idea that after she left, her student would become the most ruthless tyrant in the history books. She had even less idea that after making her escape back to the Immortal Realm, she could still be dragged back (smile). When Qiu Buyu first met Yuan Zhaoyue, she wore a gentle smile and softly asked him, "Your Highness, would you be willing to become my student?" The youth lowered his eyes. "I am grateful for the Imperial Tutor's favor, but I must respectfully decline." Who could have imagined that later, this proud and solitary man would truly kneel before her and say, "From this day on, I am your sharpest sword." As if offering himself as a sacrifice, Qiu Buyu gave everything he had to her. With Yuan Zhaoyue's help, Qiu Buyu murdered his relatives and ascended the throne. After his coronation, he swiftly declared war on the neighboring nations to bring peace to the land. When the last nation fell, Qiu Buyu rode hard for three days from the frontier, returning in a cloud of dust to share the joyful news of his unification of the land with his teacher. But he was met by a cold, empty throne room, silent and still. Perhaps his teacher was just playing a joke on him? Qiu Buyu thought. So he waited. A month, half a year, a year, three years, five years... At last, Qiu Buyu understood completely. His teacher had left. She would never come back. Not ever. - She had the most beautiful face in the world, and the cruelest heart. Theme: Treat people sincerely and act with honesty, and you'll see things through to the end