MTL - Chapter One of the Night - Chapter 62 pay the bill

Master said, the woman I held in my hands, I must protect for the rest of my life.

Master said, it’s hard to cultivate as a Demon, and once you enter the Demon Dao, you should never look back.

Master said, Heaven is a Circle and the Earth is a Square; that Circle represents (is) consummate perfection, and that Square represents (is) the edges and corners of one’s Heart, it’s a rebellion against Fate, a Disobedience to Heaven.

My master is named Ning Fan, he’s not a person, he’s merely a Butterfly who has entered Demonhood. He was searching for someone. No one knew who he was searching for. No one knew how long he would search for…

- Description from novelupdates

The first time they met they had battled fiercely, just for a mere bunch of herbs. She needed it to save people, and he wanted to use it to save his own life.

“Let go of it, or you will die.” The man’s violet eyes were cold and sinister as he said in a low voice.

She held on tightly to the base of the herb and pulled its roots right out of the ground, before she turned her eyes back with a crafty smile. “It’s mine now. Snatch it from me if you can.”

When they met several years later they were no longer on opposing sides in hostility. In order to repay the debt for having stolen the herb back then, she went on to miraculously cure his body’s condition, relieving him of the inhumane torment that wrecked at his body day and night. He was amazed by the godly skills in Medicine she possessed and his heart went on to fall irrecoverably head over heels in love.

- Description from novelupdates

There are always four kinds of people in the traditional Mary Sue world. The Male Lead, the Mary Sue female lead, the woman who never wanted to see the female protagonist live a good life, and the infatuated man willing to destroy heaven and earth to get the female lead.