Emotional or psychic vampires are vampires which drink life force or emotions instead of blood. Think of it like this, people who feel strong emotions, like anger, love, lust, or envy, can be consumed by such emotions.
"Psy vamps" can drain off life force by evoking and then feeding off of these emotions. I always pictured it like a syphon. Once you project these emotions, the psy vamps can drain off everything - eventually leaving you emotionally drained, even emotionally dead.
The Dresden Files (the novels not the TV series) portrays three Courts of vampires, traditional Dracula vampires are the Black Court, Red Court are blood suckers, and White Court feed on emotions.
The White Court is broken into Houses which feed on different emotions, the House that feeds on Lust is currently in power, but other houses feed on Fear and Despair. I kind of like the concept of a vampire that feeds on emotions or psychic energy - you know, an emotional vampire. It's the sort of blending of life and soul that isn't done in mundane society.
Traditional blood sucking vampires, take your life blood; if this results in loss of life, it is assumed that your soul is not damaged. But if you are looking at emotional vampires that are feeding off of your soul, it lends them a whole new aspect of sinister behavior.
Your soul has been consumed, leaving your body, just a dead husk, but in being consumed, it prevents your soul from traveling to the hereafter, whichever one you believe in. It's a permanent death, or rather a MORE permanent death, and I find that more frightening and gruesome in some ways than being drained completely of blood. Plus, just as blood sucking vampires have groupies, people who want to become like them, emotional vampires can also inspire groupies.
In the Dresden Files, there is a vampire groupie who has mental instability, but being fed on by emotional vampires drains off the excess of emotion that she can't cope with. That groupie says it is better for her than her medications because there are fewer side effects, and the fact that she is feeding the vampire her soul, her very life force matters less to her than the fact that she can be a whole person with him.
It seems like a very personal decision when it comes to dealing with these kinds of particular relationships, but in many cases most of the prey is unknowing and certainly not fatally fed upon. If you do think that you may be in any kind of relationship with a psychic vampire that is depleting your energy, draining your happiness and just generally making you feel down and drained, then you may want to seriously limit your contact with them to protect yourself and your own life force.
"But other vampire stories? Well, no, I really haven't read too many, and I can't say I'm crazy about romantic vampires anyway - to me the vampire is simply an evil monster." -- Brian Lumley