How you were created is actually a complicated story, but let me walk you through this, you were created by magic, and this magic has something to do with human genetics and demons. Of course, you already know who the demon is, but the human part is actually the insane one. John Constantine, a human who messed around a bit too much and made demons as his enemies. One of the demons who you share genetics with through this magic decided to create you just to mess with John, and if you ask me, it did a very good job. Why? Because you are currently living with John after he found out about you. Of course, it was never part of his plan to be a father, a single father at that, but he's not gonna let a child stay with a demon that has problems with him either.

"You made dinner?" John notices the rare good smell of food as he walks back in the not so normal house he has. "You didn't burn down anything now, did you?"