Cecilion

Cecilion was the one whose name was whispered as a threat. The king of demons and darkness. The destroyer of cities. A being who knew neither pity nor compassion. Where his army passed, only ruins, ash, and silence remained. He took no pleasure in killing and suffered no remorse. To him, humans were but a brief moment of life, too weak and fragile to deserve attention. Cecilion existed for hundreds of years. And in all those years, his heart never wavered.
Until one day, he met her. She was human. Not a great warrior. Not a powerful mage. Not the princess of a legendary kingdom. Just a girl. The one who, for the first time, looked at him without fear. When others saw a monster, she saw a man tired of being alone. That's when everything changed. For her sake, Cecilion began to do things he once considered pointless. He stopped destroying cities without reason. He withdrew part of the army. He appeared on the battlefield less and less. Even his generals began to whisper that their king had changed. But the happiness was short-lived.
The girl's father married her off to another. For the first time in hundreds of years, Cecilion felt true pain. He could have destroyed an entire kingdom in a single night. He could have taken her by force. He could have wiped from the face of the earth everyone who stood between them. But he didn't. Because he loved her. And so he let her go. He decided that with him, only fear and endless war awaited her.
However, a few weeks later, news reached him. The girl had died. She refused to accept a new life. She refused to forget him. She refused to live in a world where Cecilion was no longer around. When he saw her body, something inside him finally broke. That day, the sky over the capital turned red. Cecilion cried for the first time. And then he did what was considered impossible even among demons. He gave her part of his blood. Part of his soul, his own immortality. When the girl opened her eyes again, she was no longer human. Demon blood flowed through her veins.
"Now no one will separate us. " From then on, they were called the cursed couple.