What does anyone think of drinking a cup of water after someone else has drunk from it? (Besides the risk of sickness).
Will their dna and energy be easier to contact if you take their dna, (germs and all) into you?
Is their a technique to utilize their energy through the liquid (and food)?
Uhh i really doubt that it would be so easy, isn’t there little traces of people’s dna in the air even? so if you are breathing in same space you are having that person’s dna in that case too… But i personally wonder what would this work if you actually drink/eat that person’s blood, or/and make that person drink your blood.
I don’t know much about this path, but i wanted to give answer of my logistical thinking.
Think how many dirty people’s dna is all over you when you go in a bar for instance… sweat on the tables and shit, when you share a smoke with a regular drunkard there - do you think it really gives you special energy connection. I certainly hope not.
Well Black Flame, the same can be said for any sort of sympathetic magick. I mean hell, what good is blood when you got trace DNA of the person at work… should really be the same thing. The only difference is that blood is perceived as more important than trace spit, but overall it should be able to serve as a sympathetic link either way.
With that said, I don’t think it has any inherent power. You could use that connection as tether, but again, it would be what you make of it. I would say that if you could do it with something like that, then you probably need nothing at all to link them to you. However, I don’t feel like you need anything at all period, so shiiiiiiiii…
Well i would consider blood much more valuable material, as it is at least for me mentally much more special than spit or something alike.
Spit is spit, blood is blood, as water is water, and wine is wine.
Also getting of the blood is harder, so the part of getting that “rarer” material is ritualistic in my eyes.
But also then again, when it comes to the vampirism i still don’t know what the whole point is other than getting energy which you can get in easier than occult ways so i don’t still see the point anyways 
Completely different if you could be actual vampire like in story of Dracula.
Best thing i can think of using astral vampirism, is against other astral vampires.
I am assuming that the spit has their energy and dna imprint which can create a connection to the person/people. Maybe it would be easier than trying to hook up cords to a person from a person.
Also, I am wondering if getting their dna through the saliva would help astablish a link to their abilities both natural and spiritual. Of course that includes their faults and problems mental, physical and all that.
Kind of like getting energy from a fetish item from a sorcorer. Only without the other person knowing about it.