Demona is a villain of "The Sixth Sense". Craving power, she was summoned Dimitri, something she actually hadn't intended to do, and made a Faustian deal with him, her soul for power! He granted her request and she has served him ever since. Since then she has hunted the "gifted" and handed them over to either the authorities or Dimitri-if he wants them...
Having become Dimitri's slave was all fine and dandy for awhile, but Demona is power hungry and won't settle for being a servant and is attempting to find a way out of her servatude without losing the powers Dimitri gave her.
When Dimitri was captured by Proteus, Demona easily overcame the guards and freed her master after he agreed to grant her anything she desired for his freedom.
When Demona made her deal with Dimitri he granted her the ability to use magic to manipulate the world around her. She can create matter and use energy to attack her enemies.
She has exellent hunting skills that allow her to track down the "gifted" and capture them.
She also always keeps her eye out for anything that will enhance her powers-such as any magical items.