In the course of occult spiritual development, eventually, you will encounter true energy vampires. From Wikipedia:
A psychic vampire (or energy vampire) is a creature in folklore said to feed off the "life force" of other living creatures. The term can also be used to describe a person who gets increased energy around other people but leaves those other people exhausted or "drained" of energy.[1] Psychic vampires are represented in the occult beliefs of various cultures and in fiction.
Now, this idea has entered popular culture and is particularly associated with Narcissists. This is typically diagnosed as someone you don't like who leaves you drained. Here's a monk's explanation and suggestion for dealing with this mundane type of vampire:
Good advice but, the temptation to overdiagnose this problem and assume a victim stance toward everyone who doesn't blow a ray of sunshine up your derriere is common, like any other pop-psychology idea poorly understood and then applied by the public. Unlike a true vampire, the narcissist needs to witness their effect on you. They might be draining to deal with, but they are feeding their ego on how they can manipulate your feelings, not piercing your energy field to metaphysically drain you. A narcissist may also be a real vampire, in which case their effects are much much worse.
Your typical vampire is, like the monster of folklore, a victim of another vampire, and their habit of draining the life force is relatively unconscious. Unfortunately, the ranks of these are multiplying quickly among the aging Boomers, who with their obsession with eternal youth, are turning to practices like physically injecting the blood of the young. If this isn't vampirism nothing is but it isn't the only danger multiplying in the world. Some try-hard edgelords of the occult world are actually training themselves in vampirism, and happily trade their insights with dark-energy workers, many of whom are already con artists:
Now, both of these kinds of vampires are slipping from mundane Debbie downers to becoming a real metaphysical parasite, but there are worse. Real energy vampires in human form walk the Earth and descend from clans of historical vampires. They don't necessarily drink blood, though they may bite once to symbolically act out the piercing of the victim, but once attached continue to drain lifeforce no matter the distance from the victim. I know this because I am one. I overcame my natural tendency to vampirize through pranayama and meditation. I recall my first victims started in daycare, and I didn't stop seeking out others' vitality until I started Yoga and started analyzing my life force. I was preyed upon by my mother, who was drained by her father, who was victimized by his mother, and at that point, records are lost, but you can bet this behavior goes back to our origins in Europe. One funny aspect of this that pops up in DNA analysis, is that the non-LDS vampire side of my family has been following the migrations of the Mormons without becoming of Mormon stock until a few crossed over after forgetting their origins. Evidently healthy Mormons with their documented glow of vitality and lack of traditional knowledge make perfect food for the vampire, one of their own even glorifying the vampire clan in the Twilight series.
Now, these vampires are mortal, though they may age more quickly or more slowly than average depending on how willing they are to create true victims and the amount of Prana they harvest. You can locate them in families that seem to have non-genetic histories of blood and immune disorders. Their actions cause medically observable effects like leukemia and severe anemia or merely an inexplicably sickly child. You can see their victims in children once strong, healthy, and beautiful that grow stunted, twisted, and ugly compared to the promise they showed in youth. Many of their victims become thin and wasted and obviously drained, but some try to remedy their state with high-calorie food only to become fat and lethargic.
The current mores of our society forbid us killing this type of vampire, though, in certain parts of the world, they would be dealt with summarily. The vampires themselves contribute to a mythology that sees them as a remnant of old folklore and not a real problem. If cornered they will try to point out how "good" they are, and how they couldn't possibly be draining you to death. Don't be fooled. If a vampire won't voluntarily seek out a positive solution to their effect on others they need to be shut out of their victim's energetic field. Protective spells and energy work are necessary to sever the link and repair the holes in the aura. If ignored, or like the monk above recommends just avoided, their unexplained sicknesses and untreatable illnesses will continue until the victim dies, and it won't be nearly as funny as this:
For further resources see Psychic Self-Defence by Dion Fortune