|Although this article is based on canonical information, the actual name of this subject is conjectural.|
- "- Herein lies your truest strength.
- The energy of the Demon. Its spirit.
- Its heart.
-This is how you...
- Created the First Slayer? Yes."
- ―The Shadow Men and Buffy Summers[src]
The demon's exact origins are unknown. At some point in the past, it had been captured and controlled by the Shadow Men, who would use it to create the First Slayer.
The Era of Sineya
The Shadow Men chose a girl named Sineya to contain the power of the demon. They chained Sineya to the ground so that she could neither defend herself nor escape, then unleashed the demon, which appeared to be in the form of dark black energy vapors. It forcibly merged itself with Sineya, granting her superhuman strength, speed, reflexes, agility, superior healing factor, a predator instinct, innately formidable combat techniques and quite possibly some kind of advanced prophetic ability. However, the process also caused the First Slayer to lose touch with her own humanity forever.
War Against the First
Thousands of years later, the Shadow Men tried to repeat history with Buffy Summers in order to empower her even more so she would be able to defeat the Turok-Han army of the First Evil. However, Buffy sought knowledge, not power, especially if that power meant that she would lose her humanity. She repeatedly denied the entry of the demon into her, forcing it and keeping it out. Buffy then broke free from her chains to stop the Shadow Men, thus effectively incapacitating the shadow demon.
After she was shown the Turok-Han army, however, Buffy had doubts on whether she should have accepted the increased strength that the demon would have given her.
Powers and abilities =
The Shadow demon bestowed Sineya, the first Slayer, with the Slayer powers.