Psychic Vampyers are(normal)people who drain others of there energy (normally in mean ways but not always) they often dont even know that they are doing it.
there are also some who clame to feed off sex.
"The Satanic Bible" has a lovely chapter on it.
"The Psychopaths Bible" deals with it a little if I remember right.
heres the wiki: http://en.wikipedia.org/wiki/Psychic_vampire
Its quite simple. If you can pull energy from the earth or the sun or water ect... then you can most certainly pull from people. If you wish to know more i highly suggest reading Vampires: The Occult Truth by Konstantinos. He is a highly respected author and one of my absolute favorites to read.
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Crystals can be a very effective way to help protect yourself against psychic
intrusion, psychic attack, or psychic vampires. below you will find a list of
the most popular crystals and stones used for this purpose.
Amethyst: Protective against dark energy.
Banded/Zebra Agate: Good for general psychic protection and to prevent you from
absorbing another's negativity.
Black Moonstone: Good for general psychic protection.
Black Obsidian: Good for basic psychic defence.
Black Onyx: A good aid to grounding.
Blue Aventurine: Protective against psychic vampires.
Blue Tiger Eye: Protective against negative energy for healers.
Brown Tiger Eye: helps protect against unwanted spirits.
Brachiated Jasper: A good psychic shield that returns negative energy to the
sender.
Calcopyrite: It is generally protective against psychic attack.
Carnelian: Protective against psychic intrusion.
Chiastolite: One of the best for all-round psychic protection.
Citrine: Helps clear negativity caused by ghosts.
Clear Quartz: it is protective against negative energy and will transmute it to
positive energy.
Garnet: Good for general protection.
Green Moss Agate: It will protect your aura from negativity.
Hematite: Good for grounding and general protection.
Howlite (Natural): Protective against unwanted ghosts and phantoms.
Kyanite: It is THE anti-negativity stone. It doesn't just repel it, it destroys
it.
Lapis Lazuli: An all-round protective shield.
Mookaite: It is protective against negativity. Mookaite should also be carried
when dowsing.
Red Jasper: A good psychic shield that returns negative energy to the sender.
Red Tiger Eye: Protective against the evil eye.
Rhodonite: It can be used to ward off negativity and psychic attacks.
Rose Quartz: Another good stone to help with grounding.
Phychic vampires are those who feed off energy, I do it sometimes to those who allow me, or if I'm feeling weak and feed off enemies, sometimes I realize I did it and give it back (it's hard to give back) one if my friends feeds off consenting lovers
Mmmm I believe there is the trained method through practiced and learned techniuqes ,or the awakened, innate vampire . through psychic connection the donors emotion is vampirized .Emotion blended with aura,chi,energy,life force etc ..,can become addictive or life giving .The moral of consenting donors and random feeding is debated, now with the surge in vampiric consiosness im sure theres no shortage of willing donors, you know who you are,so next time your out be prepared to either show your neck or touch the crystals in your pocket.
Read this article it contains a lot of info on them..including a way to protect yourself from their attacks http://www.llewellyn.com/journal/article/513
I find it's mainly people that are always seeking to create arguments and trigger emotionally charged responses from people like spirits they feed of it. Unfortunately I know many of them that don't even know their doing such a thing and it really does drain you on many levels.