This is what happened in Jack's childhood. Jack's parents used to be demon aristocrats. Defeated by Gods, they had been severely wounded and relegated to plebeians.
To get revenge, Jack's parents gave birth to Jack and trained him rigorously. Whenever Jack let them down, his parents would punish him without mercy.
Jack grew up in violence and hatred. His future had been decided by the parents - vengeance on the Gods. The young Jack began to realize he was just a killing machine for his parents, but his life changed since he met her...
One day, Jack was beaten up for failing to accomplish his parents' quest. He was black and blue.
When he came home, Jack saw three sturdy men trying to rape a blue-haired girl. Jack could not tolerate it and promptly saved the girl -
Normal humans were no match for Jack. He had beaten up the men no sweat, but his face had been scratched and bleeding during the fight. The blue-haired girl came close to Jack and licked the blood off his wounds.
Jack did not feel disgusted. Rather, her cold hands soothed the pain inflicted by his parents. Elizabeth the Noble: Thank you for saving me, young gentleman. But who left these scars all over your body? They aren't from these perverts, I suppose... Jack the Gentleman: My parents did this. They punished me because I let them down. Elizabeth the Noble: Bullshit! Why do you have to satisfy their expectations? Your life belong to you, not your parents. You can do what you want to! Jack the Gentleman: Do what I want to... Elizabeth the Noble: That's right...Since I owe you a big favour for saving me, I'll do whatever you like.
Elizabeth took the young Jack for a stroll in the town. He had a wonderful time with her. The sky getting dark and Jack needed to go home. He gripped Elizabeth's stone-cold hands, unwilling to let go. Elizabeth the Noble: Hm, here, take this. Treat it as my doppelgänger.
Elizabeth bid farewell to Jack and returned to her town. Jack hugged the doll in joy as he went home. When he opened the door, his parents were standing in the doorway, ferocious. Mother: Where have you been!? What't that in your hands... A doll! We Demons don't need such ugly things! You must take the filthy Gods drown in future to glorify our kind! Jack the Gentleman: ...I'm not your toy!
The last straw was when Jack's mother tried to snatch his doll. He gathered elemental power and launched a lighting arrow at his mother's head.
His father immediately pounced on him, but Jack turned around and stabbed his father in the throat with a dagger.
Jack stared at the parents' corpses, with Elizabeth's doll in his arms. Time turned the bodies cold. This unliving temperature reminded Jack of the hands of the blue-haired girl.
He laid his cheek on his mother's and closed his eyes in ecstasy. Jack the Gentleman: I get it now. Corpses will never hurt me. This cold soothes my soul...