Soulmates.

An Angel Without Wings

"How did this start?" Dustin asked, shaking the rain out of his hair. Luca smiled, pulling his jacket off.
"When I was born, my parents were assumed to be soul mates. But my mother met a man. Tall, dark hair and eyes, handsome, as she said. She had an affair with him behind her husband's back. I was the result. When I was born, he came to see me once. This," Luca pulled on the collar of his shirt, revealing a burn or a scar on his shoulder. "Was burned into my shoulder. It won't go away."

"Why didn't you tell me?" Dustin asked.
"I thought you'd leave if you knew," Luca admitted. "I can control fire, I can disappear and reappear... My father, I mean.. Azrael. He's come to visit once. I was 12. He explained everything to me. I have to obey."
"Lu, you can't listen to him. You can't destroy the world."
"I'm sorry, Dustin. But you need to leave. I have to."
"Luca -"
"No. This isn't going to work. You need to leave."