"Feeding"
Both blood-drinking and psi-draining HLV's use the term "feed" to refer to what they actually do. Representatives of both groups have made strong statements to the effect that "feeding" (on blood or "energy") is what makes a Human Living Vampire what it is, and that other identifying "traits" or characteristics (if any) are of little or no importance. However, the function that "feeding" serves for these individuals, why it is necessary and what concrete value the substance fed upon has for the HLV who is feeding, remains a mystery and is rarely explored by the HLV's themselves. "Feeding" appears to be a given; an HLV must feed, feels a compulsion to do so, in the case of psychic vampires may do so involuntarily, and yet nobody seems to understand why.
The term itself--along with the implicit meaning--derives from the 20th Century Vampire Myth, where supernatural vampires usually cannot consume ordinary food and drink, but must have a regular intake of blood for basic nourishment. Although the supernatural vampire is said to "require blood to exist", rarely if ever are such vampires considered in danger of starving to death without blood. Deprived of blood, they will usually be vulnerable to losing control and reverting to a bestial or depraved mental state in which they act thoughtlessly, endangering themselves and/or doing things they regret later on. But they are at no risk of dying, or even experiencing permanent harm, from blood starvation. This makes the blood-need of 20th Century Mythic vampires far more akin to an addiction than a nutritional requirement.
"Feeding" refers to a living organism: we don't "feed" cars with gas or "feed" electrical appliances with electricity, although food acts as fuel for living things. "Feeding" also implies providing an organism with substances without which it will cease to live. Babies require light, physical touch and a hygienic environment in order to thrive, but we only talk about "feeding" a baby when we give it food, something without which it will certainly die. To "feed" something is to provide it with that specific nourishment without which it will quickly starve. But this is certainly not the case with the "feeding" of HLV's, all of whom must eat ordinary food, and drink water, no matter how much blood or "energy" they have available to them. In addition to this, there are other puzzles about HLV's and "feeding". Most blood-drinking HLV's consume human blood, but human blood tends to pass through the digestive tract largely unprocessed, meaning that any purely nutritive content it may have (such as proteins or iron) is mostly lost. Further, few blood-drinking HLV's consume a large amount of blood at any one time, or "feed" with any frequency approaching even once per day. Obviously, blood consumption could not be serving a nutritive purpose for a living organism as large as an adult human being. And yet, the connection of blood with "feeding" is so strong that I have never, to date, heard of a blood-craving HLV who introduced blood into his or her system by any other means than direct ingestion (drinking)--who used, for example, injection, as was depicted in the film, "The Addiction". The blood must be drunk, in spite of the fact that it cannot be digested and that only small quantities (in comparison with the frequency and amounts of food that an adult human being needs) are consumed. What function, then, does the blood serve? If blood-need is an addiction, why would injection not be an even more efficient way of absorbing it? If blood-need is nutritive, why do such small quantities (by comparison with food needs) satisfy the craving? The issues become even more complicated when some blood-craving HLV's assert that only the communion of taking blood from a consenting human donor, sometimes during sex, is truly satisfying to them. The questions raised by pure "psi-feeding", in this context, are even more conflicted.
Nevertheless, all HLV's consider what they do to be "feeding", as though it had a nutritive or sustaining effect. They do not like to think of themselves as addicts, perhaps because of the strong negative associations with addiction in American society. In some ways, they may be analogous to insulin-dependent diabetics, requiring a vital substance that their system lacks and that must be externally provided. However, diabetics and others dependent on such daily medical regimens will die if they are deprived of their prescribed substance. I have never heard of an HLV being in danger of death for lack of blood or "psi energy". If even the worst blood-needing HLV's were in such a position, we would expect to have heard of some who were hospitalized for lack of blood. However, although some blood-needing HLV's report "withdrawal" symptoms so severe as to make them wish they could die, this threat does not seem to be a factor in their situation. The "need" that HLV's experience is for a fix, not a meal.
The chief (indeed, overwhelming) concern for most HLV's seems to be how to "feed" more efficiently, how to find "donors", how to guarantee a regular supply of the needed substance, and so forth--very similar to drug addicts. Very few wonder why they need what they need, this seeming to be entirely beside the point--just as it is a rare drug abuser who is interested in the physiology of his addiction. With addiction, nothing matters but getting the next fix, and how awful it feels not to get it. But if the addiction is considered a legitimate biological need, equivalent to one's hunger for food, then some of the psychological sting is soothed. Some blood-craving vampires, in particular, are very hostile to suggestions that anything else but fresh, living blood from a live donor could satisfy their needs. The possibility that some in-depth research might produce a blood-substitute for HLV's, like methadone, that would render "blood feeding" unnecessary may not be that attractive a prospect. But that is a separate issue. In the meantime, I will refrain from offering any speculations of my own on this subject and leave this mystery to be explored by the HLV's themselves. It will be interesting to see what they propose as possible explanations of why they need to "feed" and why they need to think of it as "feeding" instead of employing a possibly more exact analogy.
FEEDING