Alcastor

"I have been looking for you for a long time, love, but it's always this way. You always try to escape me, always try to leave me, and you never stay, never, and I don't understand why. I love you best. I always loved you best, even when you didn't remember my name: you'll remember me eventually, won't you? No one else will ever love you as much as or the way I love you." - Alcastor, to Ziel after kidnapping herAlcastor is Ziel's former Fiance and one of the main antagonists of the series.

Personality
Alcastor is a bloodthirsty murderer who kills as naturally as he breathes and enjoys violence. He will slay even his own followers without hesitation, be it because they disobeyed him or simply ceased to please him. The suffering he endured as a child leads him to hate the entire world, amplified by losing Ziel to Third Eye, but he doesn't just seek revenge; he simply hates and kills.

Alcastor's most prominent trait was his extreme obsession with his ex-fiance Ziel, juxtaposed with his general lack of care for any matters not to do with her. He was shown to be ruthless and cold, committing acts of extreme violence for even minor slights against Ziel, though his more petty actions seemed to be reserved for women.

Magic and abilities
Corruption Magic: Alcastor is able perform a form of magic that utilizes a form of corruption or tainted nature to a variety of effects.

Love Magic: Alcastor can utilize a form of magic dealing with love, passion, happiness, etc. She can use different spells to formulate the inducement of sex or can use emotions of love to cast different kinds of spells.

Potion Making: Alcastor can create potions: substances with magical properties such as enhancing physical and mental abilities, healing, granting powers, changing shape, or bewitching someone depending on the kind of potion that is made. Aphrodisiac Amplification: Alcastor can amplify sexuality of themselves and others, concentrate the targets overall sexuality to further increase sexual quality of anyone using energy, pheromones, etc, inducing complete sexual arousal; causing extreme lust, enhanced sensitivity to sexual pleasure and causing them to crave sexual interaction, regardless if they can feel love or pleasure. He used this on Third Eye in an attempt to make Ziel hate him, and it almost worked, if it wasn't for the fact that Ziel snapped Third Eye out of it when she noticed his eyes were pink and not red.
 * Love Potion: Combining his potion making with his love magic, he was able to make a love potion, which he forcefully made Third Eye drink. Unfortunately for Alcastor, and fortunately for Third Eye, it didn't work the way it was supposed to.

Quotes

 * “Beautiful flowers, too, eventually wither and fall. That’s the fate of all living beings.”
 * “In order to measure a person’s worth, you must do more than push them. The real way to test their worth is to give them power. When they gain the freedom to act outside the boundaries of law and ethics, you can sometimes see their souls.”