Actually, I've thought about this (okay, so I think about everything). With all the lace, accoutrement's, blood clubs, glamour goth, passions and immortal angst - well, all that's a load of (albeit delightful) crap.
No really. Imagine yourself truly immortal. At some point the desire for animal passions, for ego satisfaction, would have to cease. There would certainly come a point of absolute satiation. [And along this line of thinking, one can't help but compare angels & demons, God & demigods, et al]
At some absolute, inescapable point in the linear experience of a truly immortal (vampire or what have you) sentient being, there would and must come the moment wherein one would dispense with physical experience altogether, to become, how to put this ... a Creature of the Mind.
Boredom, satiation, insensate, you name it. There would no longer exist a desire (in other words, any possible stimulation resulting from) for physical experience. This point could take anywhere from a few days to centuries to arrive at, but its arrival would nonetheless be a given.
And while we like to assume the vampiric, immortal individual would so long (can anyone say Lestat here?) to rejoin, to reconnect with the human camaraderie left behind, to become mortal and feeling once again, I think this would be no more than a temporary nostalgic stage in the ongoing evolution - the continuing life experience - of an actual vampire.
Because we humans like to think that our passions and ego gratification, our desires and the fulfillment thereof, are what life's about (even though in our deepest center we fully know better). This isn't a matter of good vs. evil, its just the way things are. Whether a vampiric creature were the most self-centered being on earth, or the greatest altruist, the cycle would and must be the same for all. This state, as viewed from the perspective of a human being, would appear as amoral, when in actuality it would be better described as 'disinterested'.
That said, what happens next? What follows the abolition for physical experience? The mind, of course. All stimulation and experience would necessitate a mental channel. The truly immortal would cease to identify with the mortal, finite and physical herd, and hence go inwards, into the mental world and all that might encompass.
The amazingly talented and thoughtful Anne Rice wrote along this line of conjecture as well. However, she seemed to reach a stopping point and cycled back to where her characters did eventually, for whatever reason, seek connections, previous companionships and physical experience, to some greater or lesser degree. Perhaps this cycling was necessary in order to maintain a plot worthy of readers' continuing interest.
Fiction aside, and in terms of any potential reality, the immortal (vampire or no) must eventually lose any desire, any need for companionship, of any sort. There could no longer exist an external physical situation capable of producing the necessary stimuli/response.
All following stimulus must then be generated from within, from the mind itself. It would have to, following the above reasoning. And this mind experience would not be contained to solitary pursuits such as writing, art or music. Again, given those are physical actions, so they, too, must eventually fall by the wayside.
So, to recap and insist : a genuine immortal must as some point dispense with all things physical.
Here is where we reach a conundrum. What if the very state of immortality (such as the mythical vampiric state) requires a physical action in order to maintain its status? (blood in the case of the vampire)
Funny thing, but in the real, physical world there have been cases of individuals who somehow seem to exist on an absolute minimum of food and water, (the word autotroph comes to mind, but I've googled and can't find the exact term I'm looking for), their bodies somehow manage to recycle fluids, to literally restructure natural processes into a system of self, closed maintenance, and also to resist corruption after death (for no matter how well embalmed, most bodies are reduced to a skeletal state within a year of interment.
Any genuine factual and extant vampire (or any other type of immortal creature) would and must evolve into something non-physical. And with this action, would come a release from all desire and interest in the physical world, for no matter how interesting we mortals consider our physical existence to currently be, it is necessarily but a temporary interest.
Additionally, and most importantly perhaps, is given we have some understanding regarding how crucial the mind/body connection is in the human state of existence - stigmata and the placebo effect not withstanding - we must, however reluctantly, conclude that the more evolved-beyond-the-physical a sentient being would become, the less approachable, discernible and communicable by man such an entity would have to be.
A true immortal, those beings no longer subject to the constraint of seeking outside energetic nourishment and replenishment for self maintenance (and this too, would be an ever evolving state) must, to some greater or lesser degree, become closed systems in and of themselves. Entropy would cease to be an issue (and with it the laws of thermodynamics).
Where intelligence and self-awareness would fit into such a picture is a matter for speculation, and is it a state we, here in the physical, would actually find desirable?
I don't think so, at least not within our present ego situation. For quite likely there would also follow a dispense with the ego awareness altogether.
I suspect that a real and completely immortal being would and must morph into a creature we would have no commonality with, no recognition of, and scarcely a hope on which to find a meeting ground.
And, to take this conjecture another step onward, isn't this where our myths, legends and religions attempt to describe the ineffable? Would it be accurate to state that the more highly evolved an entity is, the less interested it would be in anything beyond its enclosed system of self? Would such an entity, eventually, even be aware there existed anything outside itself?
This is where I harken back to a few of those especially remarkable accounts of the DMT volunteers as chronicled in the book by Rick Strassman DMT The Spirit Molecule [by all means, this is a must read].
So in conclusion, we, ourselves, might consider dispensing with all minor physical tricks and toys in our attempt to flush out, to contact the truly immortal. Unless we wish to waste our time with beings no better off than ourselves, or at least not far beyond our own rung on the physical/soul evolutionary ladder, it would seem that any hope for valid contact with these conjectured entities must lay within the capabilities of our very own mind/s.
And this would include all contact, beyond an individual's sheer curiosity, with energy feeders, psychic vampires, demons (I use this label in the loosest sense), etc etc. These feeders would not be a particularly highly evolved class of beings, which goes a long way to explain most human/other interfaces. And anything or anyone requiring/suggestive of adulation, sacrifice, abject worship et al. would fall into this class of 'energy feeding', I believe, for what else would necessitate such focus?
Anyway, funny how 'That' with the least cause for interest in man is also that which man is, ultimately, the most intrigued by. What a paradox this truly is.
Therefore, if one desires contact with the ineffable, then be prepared to work/think/act beyond the physical 'box', and with the expectation of ineffable results. And sadly, a truly evolved and immortal being may quite possibly lay beyond our limited means to make any such contact with, period.